Imaging and tools for use with moving organs

ABSTRACT

Apparatus is described for use with a portion of a subject&#39;s body that moves as a result of cyclic activity of a body system. An imaging device acquires a plurality of image frames of the portion. A sensor senses a phase of the cyclic activity. A medical tool performs a function with respect to the portion. A control unit generates a stabilized set of image frames of the medical tool disposed within the portion, actuates the tool to perform the function or move, in response to the sensor sensing that the cyclic activity is at a given phase thereof, and inhibits the tool from performing the action or moving in response to the sensor sensing that the cyclic activity is not at the given phase. A display facilitates use of the tool by displaying the stabilized set of image frames. Other embodiments are also described.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present patent application claims the benefit of U.S. ProvisionalPatent Application Nos. 60/906,091 filed on Mar. 8, 2007, 60/924,609filed on May 22, 2007, 60/929,165 filed on Jun. 15, 2007, 60/935,914filed on Sep. 6, 2007, and 60/996,746 filed on Dec. 4, 2007, all named“Apparatuses and methods for performing medical procedures oncyclically-moving body organs,” all of which applications areincorporated herein by reference.

The present application is related to the following applications, whichare incorporated herein by reference:

-   -   a U.S. patent application, entitled “Imaging for use with moving        organs,” to Tolkowsky et al., which is filed on even date with        the current application.    -   a U.S. patent application, entitled “Tools for use with moving        organs,” to Iddan et al., which is filed on even date with the        current application.

a PCT Application, entitled “Imaging and tools for use with movingorgans,” to Iddan et al., filed on Mar. 9, 2008.

FIELD OF THE INVENTION

The present invention generally relates to medical apparatus.Specifically, the present invention relates to stabilizing imaging ofcyclically moving body portions and synchronizing the actuation and/ormovement of tools with the cyclical motion of cyclically moving bodyportions.

BACKGROUND OF THE INVENTION

Continuous images of a cyclically-moving body organ are typicallydisplayed in the course of many medical procedures such as proceduresperformed on the heart, the thorax, the respiratory tract, the eyes, orthe cardiovascular system. Such images typically shift constantly andare also prone to blurring. Consequently, such images are typicallydifficult to observe, and are difficult to use in making clinicaldecisions over an extended period of time (such as the entire durationof the procedure).

Many procedures are performed with respect to moving body parts, forexample the insertion of balloons and stents into moving blood vessels.A difficulty associated with such procedures is the targeted deploymentand/or actuation of tools with respect to the moving body part.

U.S. Pat. No. 4,865,043 to Shimoni, which is incorporated herein byreference, describes a data selection method and system using aplurality of multi-dimensional windows wherein two parameters of ECGsignals are tested for determining whether the imaging data receivedsimultaneously with the ECG signal is to be accepted. The plurality ofwindows are described as providing a capability to gate and to sortimaging data based on the passage of associated ECG signals through eachof the plurality of windows with different parameters. Thus images aredescribed as being reconstructed for a population of abnormally short orlong heart cycles from a common data pool.

U.S. Pat. No. 3,954,098 to Dick et al., which is incorporated herein byreference, describes a scan converter storage surface which is dividedinto image spaces corresponding to different points in the heart cycle.Ultrasound echoes from heart structures are plotted in the image spacesby means of special x, y sweeps which are offset to the image spaces bytiming circuitry.

U.S. Pat. No. 4,382,184 to Wernikoff, which is incorporated herein byreference, describes X-ray apparatus and methods for producing discreteimages of a human organ in fluctuating motion, e.g., the heart andrelated vessels. Each image is derived at a selected time related to thecardiac cycle. The images are independently presented on respectivediscrete areas within a common image plane. A source of X-raysirradiates the organ. A physiological synchronizer produces timingsignals within the cardiac cycle for controlling the periods oftransmission of the X-ray beam through the organ during, for example,end diastole and end systole. An anti-scattering, masking frame hasalternate parallel slits and bars at equal intervals exposingsubstantially half the area of presentation of an X-ray sensitive filmin alternate, equally spaced area strips during, e.g., diastole. Theframe is repositioned in response to a signal from the synchronizer foractuating it relative to the film, such that the bars then cover thesensitized areas of the film and expose substantially the remaining halfof the film during systole. The image elements are interdigitallyjuxtaposed to present the diastolic and systolic images in an interlacedpattern. Relative displacements of the organ during a cardiac cycle maybe determined from the juxtaposed image elements.

U.S. Pat. No. 4,016,871 to Schiff, which is incorporated herein byreference, describes a system which is capable of simultaneouslydisplaying a plurality of waveforms on the face of a CRT which arerepresentative of ECG, arterial pressures and operating states of themechanical heart assistance devices, as well as a “timing bar” whichsweeps across the CRT face in synchronism with the ECG trace, forexample. Optical pickups are slidably mounted adjacent the CRT faceacross the path of the “timing bar” sweep for activating photodetectorswhich in turn initiate inflation and deflation of mechanical assistivedevices at any desired point along the ECG or pressure trace. Any one ofthe pressure or ECG traces may be “frozen” on the display face tofacilitate comparison between a trace of the condition of the heartprior to the use of heart assistance and a trace of the augmentedcondition. All traces may be freely moved to any location upon thedisplay face so as to permit close positioning and even superimpositionof two or more traces to still further facilitate visual comparisons.The timing bar may also be utilized to provide an electrical pacingassist for controlling patient heart rate as well as for extending theheart refractory period enabling the assistance devices to operate atreduced rates.

U.S. Pat. No. 3,871,360 to Van Horn et al., which is incorporated hereinby reference, describes a system for timing biological imaging,measuring, or therapeutic apparatus in accordance with selectedphysiological states of a subject, featuring in various aspectsgeneration of respiratory windows on the basis of processed electricalsignals derived from prior respiration history, digital offsetcorrection circuitry for the respiratory signals, and generation ofcardiac timing signals on the basis of prior cardiac cycle history.

U.S. Pat. No. 4,031,884 to Henzel, which is incorporated herein byreference, describes apparatus for correlating the respiratory andcardiac cycles includes a circuit for defining a chosen period in theprogress of the respiratory cycle as the end of a regulatable delaybeginning when the ascending front of the inspiratorial pressure reachesa regulatable level as well as a circuit for defining a chosen period inthe progress of the cardiac cycle as the end of a regulatable delaybeginning when the differential dV/dt of the blood pressure reaches aregulatable level. An operator such as a terminal relay is activatedupon the coincidence of these two periods in time after a regulatabledelay and during a regulatable period.

U.S. Pat. No. 4,994,965 to Crawford et al., which is incorporated hereinby reference, describes a method of reducing image artifacts intomographic, projection imaging systems due to periodic motion of theobject being imaged, and includes the acquisition of a signal indicativeof the periodic motion. This signal is used to identify a quiescentperiod in the periodic motion so that the acquisition of projection datamay be coordinated to be centered within the quiescent period.

U.S. Pat. No. 4,878,115 to Elion, which is incorporated herein byreference, describes a method in which a dynamic coronary roadmap of thecoronary artery system is produced by recording and storing a visualimage of the heart creating a mask sequence, recording and storinganother dynamic visual image of the heart after injection of a contrastmedium thereby creating a contrast sequence, matching the differentdurations of two sequences and subtracting the contrast sequence fromthe mask sequence producing a roadmap sequence. The roadmap sequence isthen replayed and added to live fluoroscopic images of the beatingheart. Replay of the roadmap sequence is triggered by receipt of an ECGR-wave. The result is described as a dynamically moving coronary roadmapimage which moves in precise synchronization with the live incomingfluoroscopic image of the beating heart.

U.S. Pat. No. 4,709,385 to Pfeiler, which is incorporated herein byreference, describes an x-ray diagnostics installation for subtractionangiography, which has an image memory connected to an output of anx-ray image intensifier video chain which has a number of addresses forstoring individual x-ray video signals obtained during a dynamic bodycycle of a patient under observation. A differencing unit receivesstored signals from the image memory as well as current video signalsand subtracts those signals to form a superimposed image. Entry andreadout of signals to and from the image memory is under the command ofa control unit which is connected to the patient through, for example,an EKG circuit for identifying selected occurrences in the body cycleunder observation. Entry and readout of data from the image memory isthereby controlled in synchronization with the selected occurrences inthe cycle.

U.S. Pat. No. 4,270,143 to Morris, which is incorporated herein byreference, describes a cross-correlation video tracker and method forautomatically tracking a relatively moving scene by storing elementsfrom a frame of a video signal to establish a reference frame andcomparing elements from a subsequent frame with the stored referenceframe to derive signals indicating the direction and angular distance ofscene relative movement. A cross-correlation difference signal isgenerated which represents the difference between a pair ofcross-correlation signals dependent on the correlations of thesubsequent frame elements and the stored reference elements at twopredetermined opposite relative shifts. A circuit is responsive to thisdifference signal for generating an error signal indicative of theamount of shift required to center the stored reference frame withrespect to the subsequent frame.

U.S. Pat. No. 4,758,223 to Rydell, which is incorporated herein byreference, describes a hand-operated device for inflating the expanderon a balloon-type catheter and for perfusing fluids through the catheterand out its distal end.

U.S. Pat. No. 4,723,938 to Goodin et al., which is incorporated hereinby reference, describes an inflation/deflation device for an angioplastyballoon catheter which permits quick inflation to an approximate workingpressure followed by a fine but slower adjustment to a final desiredpressure.

U.S. Pat. No. 6,937,696 to Mostafavi, which is incorporated herein byreference, describes a method and system for physiological gating. Amethod and system for detecting and estimating regular cycles ofphysiological activity or movements is also disclosed. Another disclosedembodiment is directed to predictive actuation of gating systemcomponents. Yet another disclosed embodiment is directed tophysiological gating of radiation treatment based upon the phase of thephysiological activity. Gating can be performed, either prospectively orretrospectively, to any type of procedure, including radiation therapyor imaging, or to other types of medical devices and procedures such asPET, MRI, SPECT, and CT scans.

U.S. Pat. No. 6,246,898 to Vesely et al., which is incorporated hereinby reference, describes a method for carrying out a medical procedureusing a 3-D tracking and imaging system. A surgical instrument, such asa catheter, probe, sensor, pacemaker lead, needle, or the like isinserted into a living being, and the position of the surgicalinstrument is tracked as it moves through a medium in a bodilystructure. The location of the surgical instrument relative to itsimmediate surroundings is displayed to improve a physician's ability toprecisely position the surgical instrument. The medical proceduresincluding targeted drug delivery, sewing sutures, removal of anobstruction from the circulatory system, a biopsy, amniocentesis, brainsurgery, measurement of cervical dilation, evaluation of knee stability,assessment of myocardial contractibility, eye surgery, prostate surgery,trans-myocardial revascularization (TMR), robotic surgery, andevaluation of RF transmissions.

US Patent Application Publication 2006/0058647 to Strommer et al., whichis incorporated herein by reference, describes a method for delivering amedical device coupled with a catheter, to a selected position within alumen of the body of a patient, the method comprising the procedures of:registering a three-dimensional coordinate system with a two-dimensionalcoordinate system, the three-dimensional coordinate system beingassociated with a medical positioning system (MPS), the two-dimensionalcoordinate system being associated with a two-dimensional image of thelumen, the two-dimensional image being further associated with an organtiming signal of an organ of the patient; acquiring MPS data respectiveof a plurality of points within the lumen, each of the points beingassociated with the three-dimensional coordinate system, each of thepoints being further associated with a respective activity state of theorgan; determining a temporal three-dimensional trajectoryrepresentation for each of the respective activity states from theacquired MPS data which is associated with the respective activitystate; superimposing the temporal three-dimensional trajectoryrepresentations on the two-dimensional image, according to therespective activity state; receiving position data respective of theselected position, by selecting at least one of the points along thetemporal three-dimensional trajectory representation; determining thecoordinates of the selected position in the three-dimensional coordinatesystem, from the selected at least one point; determining the currentposition of the medical device in the three-dimensional coordinatesystem, according to an output of an MPS sensor attached to the catheterin the vicinity of the medical device; maneuvering the medical devicethrough the lumen, toward the selected position, according to thecurrent position relative to the selected position; and producing anotification output when the current position substantially matches theselected position.

U.S. Pat. No. 6,666,863 to Wentzel et al., which is incorporated hereinby reference, describes devices and methods for performing percutaneousmyocardial revascularization (PMR). An embodiment is described in whicha detector of an ablation controller provides a detect signal when asensor block output signal indicates that a first electrode is touchingthe wall of the heart. The ablation controller may also provide a detectsignal when the heart is in a less vulnerable portion of the cardiacrhythm, such as when the ventricles of the heart are contracting. Assuch, the ablation controller is described as helping to identify whenthe first electrode is in contact with the wall of the heart, therebyreducing the likelihood that an ablation will be triggered when thefirst electrode is not in contact with the endocardium of the heart andcause damage to the blood platelets within the heart.

U.S. Pat. No. 5,176,619 to Segalowitz, which is incorporated herein byreference, describes a heart-assist device which includes a flexiblecatheter carrying at least a ventricular balloon, such ballooncorresponding in size and shape to the size and shape of the leftventricle in the heart being assisted, the ventricular balloon beingprogressively inflated creating a wave-like pushing effect and deflatedsynchronously and automatically by means of a control console whichresponds to heart signals from the catheter or elsewhere.

PCT Publication WO 94/010904 to Nardella, which is incorporated hereinby reference, describes an ablation catheter that has an ablationelectrode at a distal end coupled to an ablation power source through alow impedance coupling. In some embodiments, ablation only occurs whilethe heart is in a desired part of the cardiac cycle, the ablation powerintervals being triggered by timing pulses synchronized with detectionof the R wave. This mode of actuation is described as assuring that theheart is essentially stationary before delivery of ablation energy, thusminimizing the risk of inadvertently ablating healthy tissue.

An article by Boyle et al., entitled “Assessment of a Novel AngiographicImage Stabilization System for Percutaneous Coronary Intervention”(Journal of Interventional Cardiology,” Vol. 20 No. 2, 2007), which isincorporated herein by reference, describes a system for stabilizingangiographic images at a region of interest in order to assist duringpercutaneous coronary intervention (PCI).

An article by Timinger et al., entitled “Motion compensated coronaryinterventional navigation by means of diaphragm tracking and elasticmotion models” (Phys Med Biol. 2005 Feb. 7; 50(3):491-503), which isincorporated herein by reference, presents a method for compensating thelocation of an interventional device measured by a magnetic trackingsystem for organ motion and thus registering it dynamically to a 3Dvirtual roadmap. The motion compensation is accomplished by using anelastic motion model which is driven by the ECG signal and a respiratorysensor signal derived from ultrasonic diaphragm tracking.

An article by Timinger et al., entitled “Motion compensation forinterventional navigation on 3D static roadmaps based on an affine modeland gating” (Phys Med Biol. 2004 Mar. 7; 49(5):719-32), which isincorporated herein by reference, describes a method for enablingcardiac interventional navigation on motion-compensated 3D staticroadmaps.

An article by Turski et al., entitled “Digital Subtraction Angiography‘Road Map’” (American Journal of Roentgenology, 1982), which isincorporated herein by reference, describes a technique calledroadmapping. An arterial roadmap for the subsequent manipulation ofcatheters under fluoroscopy is generated by means of first injecting acontrast agent into said arteries and using the resulting, “highlighted”arterial image as a background to the real-time fluoroscopic imaging ofthe catheterization procedure.

An article by Iddan et al., entitled “3D imaging in the studio andelsewhere” (SPIE Proceedings Vol. 4298 2001), which is incorporatedherein by reference, describes the technique of background subtractionand replacement of video images, which has been used in TV studios.

The following patents and patent applications, which are incorporatedherein by reference, may be of interest:

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SUMMARY OF THE INVENTION

In some embodiments of the invention, apparatus and methods are used forfacilitating medical procedures performed on cyclically-moving organs,so that such procedures are performed under a partial or full virtualstabilization of such organs. In some embodiments, the stabilizationcomprises at least one of the following elements: the stabilization ofimage(s) being viewed with respect to the motion of an organ, and theactuation of tool(s) applied to the organ in synchronization with theorgan's motion.

In some embodiments, continuously-generated image frames ofcyclically-moving organs are gated to one or more physiological signalsor processes, wherein the cycle(s) of such signals or processescorrespond to a motion cycle of the organ being imaged. Consequently,the displayed gated image frames of the organ are typically all in aselected same phase of a motion cycle of the organ.

In some embodiments, the gated images are displayed with a smoothenedtransition filling the gaps among them, generating a synthesized,continuous video stream.

In some embodiments, image tracking is applied to continuously-generatedimages of moving organs, to align such images to one another. The motionto which such tracking is applied may be cyclical, or non-cyclical, or acombination of both. The visual effect of such motion is typicallyreduced by the image tracking.

In some embodiments, a combination of the aforementioned gating,tracking and/or gap filling are applied to generate a stabilized imagestream.

In some embodiments, road mapping is applied to the stabilized imagestream. In some embodiments, roadmapping is applied to the stabilizedimage stream to facilitate a medical procedure that is performed on themoving organ.

In some embodiments, the actuation or movement of one or more medicaltools applied to a cyclically-moving organ is synchronized with one ormore physiological signals or processes whose cycle(s) corresponds to amotion cycle of the organ. Consequently, the tool is typically actuatedonly during one or more selected same phases in a motion cycle of theorgan. In some embodiments, the synchronized actuation of medical toolscontrols the application of linear motion, angular motion, energy,substance delivery, or any combination thereof.

In some embodiments, the aforementioned stabilized imaging andsynchronized tool application are applied jointly to a cyclically movingorgan. In some embodiments, images of the organ are stabilized withrespect to a given phase of the cycle, and the actuation of the tool issynchronized to the same phase. In some embodiments, this leads tovirtual stabilization of the cyclically-moving organ, both with respectto the imaging of the organ and the tools being moved and/or applied.

It is noted, however, that the scope of the present invention includessynchronized tool application and/or movement with respect to acyclically moving organ, using techniques described herein, even in theabsence of stabilized imaging as described herein, or even in theabsence of any imaging.

In some embodiments, the aforementioned techniques are applied to anorgan that may not be cyclically moving, but is cyclically active, forexample, an organ that undergoes neural cyclic activity.

There is therefore provided, in accordance with an embodiment of theinvention, apparatus for imaging a portion of a body of a subject thatmoves as a result of cyclic activity of a first body system of thesubject and that also undergoes additional motion, the apparatusincluding:

an imaging device for acquiring a plurality of image frames of theportion of the subject's body;

a sensor for sensing a phase of the cyclic activity of the first bodysystem;

a control unit configured to generate a stabilized set of image framesof the portion of the subject's body:

-   -   by identifying a given phase of the cyclic activity of the first        body system, and outputting a set of the image frames        corresponding to image frames of the portion acquired during the        given phase, and    -   by image tracking at least the set of image frames to reduce        imaged motion of the portion of the subject's body associated        with the additional motion; and

a display configured to display the stabilized set of image frames ofthe portion of the subject's body.

In an embodiment, the control unit is configured to identify the givenphase of the cyclic activity using a gating signal, and the display isconfigured to display a representation of the gating signalsimultaneously with displaying the stabilized set of image frames.

In an embodiment, the display is configured to display an enlargedstabilized set of image frames of a region within the portion of thesubject's body.

In an embodiment, to generate the stabilized set of image frames of theportion of the subject's body, the control unit is configured:

to identify a first image frame acquired during the given phase,

subsequently, to image track the first identified image frame,

subsequently, to identify a second image frame acquired during the givenphase, and

subsequently, to image track the second identified image frame.

In an embodiment, to generate the stabilized set of image frames of theportion of the subject's body, the control unit is configured:

to image track a first image frame,

subsequently, to place the first image tracked frame in the stabilizedset of image frames if the first image tracked frame was acquired duringthe given phase,

subsequently to image track a second image frame, and

subsequently, to place the second image tracked frame in the stabilizedset of image frames if the second image tracked frame was acquiredduring the given phase.

In an embodiment, to generate the stabilized set of image frames of theportion of the subject's body, the control unit is configured:

to generate a gated set of image frames of the plurality of image framescorresponding to image frames of the portion acquired during the givenphase, and

subsequently, to image track the gated set of image frames.

In an embodiment, to generate the stabilized set of image frames of theportion of the subject's body, the control unit is configured:

to image track the plurality of image frames of the portion of thesubject's body, and

subsequently, to generate a set of image frames corresponding to thoseof the tracked image frames of the portion that were acquired during thegiven phase.

In an embodiment, the control unit includes a video tracker selectedfrom the group consisting of: an edge tracker, a centroid tracker, acorrelation tracker, and an object tracker, and the control unit isconfigured to image track the at least the set of image frames using theselected video tracker.

In an embodiment, the control unit is configured to generate the set ofimage frames corresponding to image frames of the portion acquiredduring the given phase by controlling the imaging device to acquire theplurality of image frames only when the cyclic activity is at the givenphase.

In an embodiment,

the imaging device is configured to acquire the plurality of imageframes throughout the cyclic activity, and

the control unit is configured to generate the set of image framescorresponding to image frames of the portion acquired during the givenphase, by selecting image frames corresponding to image frames of theportion acquired during the given phase from the plurality of imageframes.

In an embodiment, the apparatus further includes a user interface, andthe control unit is configured to receive an input from a user, via theuser interface, and to select a phase of the cyclic activity as beingthe given phase in response to the input.

In an embodiment, the display is configured to display the plurality ofacquired image frames simultaneously with displaying the stabilized setof image frames.

In an embodiment, the apparatus is configured for the display to displaythe stabilized set of image frames in real time with respect to theacquisition of the plurality of image frames by the imaging device.

In an embodiment, the apparatus is configured for the display to displaythe stabilized set of image frames within 4 seconds of the imagingdevice having imaged the plurality of image frames.

In an embodiment, the apparatus is configured for the display to displaythe stabilized set of image frames less than two cycles of the cyclicactivity after the imaging device imaged the plurality of image frames.

In an embodiment, the apparatus is configured for the display to displaythe stabilized set of image frames during a medical procedure duringwhich the imaging device images the plurality of image frames.

In an embodiment, the apparatus is configured to display the stabilizedset of image frames subsequent to a medical procedure during which theimaging device imaged the plurality of image frames.

In an embodiment, the apparatus further includes a data storage unitconfigured to store the stabilized set of image frames.

In an embodiment, the control unit is configured to enhance thestabilized set of image frames by image processing the stabilized set ofimage frames.

In an embodiment, the additional motion is not associated with cyclicactivity of the subject's body, and the control unit is configured toreduce the imaged motion associated with the additional motion that isnot associated with cyclic activity, by image tracking at least the setof image frames.

In an embodiment, the additional motion is associated with whole-bodymotion of the subject, and the control unit is configured to reduce theimaged motion associated with the whole-body motion by image tracking atleast the set of image frames.

In an embodiment, the apparatus further includes:

a contrast agent; and

an injection tool configured to inject the contrast agent into a spacewithin the portion of the subject's body, and

-   -   the imaging device is configured to acquire at least one image        frame of the space during the given phase, at a time when at        least some of the contrast agent is present within the space,        and    -   the display is configured to display the at least one image        frame of the space overlaid on at least one same one of the        stabilized set of image frames.

In an embodiment,

the imaging device is configured to acquire a first image frame of thespace during the given phase of a first cycle of the cyclic activity, ata time when at least some of the contrast agent is present within thespace,

the imaging device is configured to acquire a second image frame of thespace during the given phase of a second cycle of the cyclic activity,at a time when at least some of the contrast agent is present within thespace, and

the display is configured to display the first and the second imageframe of the space overlaid on at least one same frame of the stabilizedset of image frames.

In an embodiment,

the space includes a lumen containing an occlusion,

the injection tool is configured to inject the contrast agent into thelumen on a proximal side of the occlusion and on a distal side of theocclusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the proximal side of the occlusion during the given phaseof a cycle of the cyclic activity, at a time when at least some of thecontrast agent is present within the lumen on the proximal side of theocclusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the distal side of the occlusion during the given phase ofthe cycle, at a time when at least some of the contrast agent is presentwithin the lumen on the distal side of the occlusion, and

the display is configured to display the at least one image frame of thelumen on the proximal side of the occlusion and the at least one imageframe of the lumen on the distal side of the occlusion overlaid on atleast one same frame of the stabilized set of image frames.

In an embodiment,

the space includes a lumen containing an occlusion,

the injection tool is configured to inject the contrast agent into thelumen on a proximal side of the occlusion and on a distal side of theocclusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the proximal side of the occlusion during the given phaseof a first cycle of the cyclic activity, at a time when at least some ofthe contrast agent is present within the lumen on the proximal side ofthe occlusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the distal side of the occlusion during the given phase ofa second cycle of the cyclic activity, at a time when at least some ofthe contrast agent is present within the lumen on the distal side of theocclusion, and

the display is configured to display the at least one image frame of thelumen on the proximal side of the occlusion and the at least one imageframe of the lumen on the distal side of the occlusion overlaid on atleast one same frame of the stabilized set of image frames.

In an embodiment,

the space includes a lumen containing an occlusion,

the injection tool is configured to inject the contrast agent into thelumen on a proximal side of the occlusion,

the apparatus further includes a second injection tool configured toinject the contrast agent into the lumen on a distal side of theocclusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the proximal side of the occlusion during the given phaseof a cycle of the cyclic activity, at a time when at least some of thecontrast agent is present within the lumen on the proximal side of theocclusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the distal side of the occlusion during the given phase ofthe cycle, at a time when at least some of the contrast agent is presentwithin the lumen on the distal side of the occlusion, and

the display is configured to display the at least one image frame of thelumen on the proximal side of the occlusion and the at least one imageframe of the lumen on the distal side of the occlusion overlaid on atleast one same frame of the stabilized set of image frames.

In an embodiment,

the space includes a lumen containing an occlusion,

the injection tool is configured to inject the contrast agent into thelumen on a proximal side of the occlusion,

the apparatus further includes a second injection tool configured toinject the contrast agent into the lumen on a distal side of theocclusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the proximal side of the occlusion during the given phaseof a first cycle of the cyclic activity, at a time when at least some ofthe contrast agent is present within the lumen on the proximal side ofthe occlusion,

the imaging device is configured to acquire at least one image frame ofthe lumen on the distal side of the occlusion during the given phase ofa second cycle of the cyclic activity, at a time when at least some ofthe contrast agent is present within the lumen on the distal side of theocclusion, and

the display is configured to display the at least one image frame of thelumen on the proximal side of the occlusion and the at least one imageframe of the lumen on the distal side of the occlusion overlaid on atleast one same frame of the stabilized set of image frames.

In an embodiment, the imaging device includes a fluoroscope.

In an embodiment, the space includes a space selected from the groupconsisting of a chamber of a heart of the subject, a lumen of a coronaryblood vessel of the subject, and a lumen of an aorta of the subject, andthe injection tool is configured to inject the contrast agent into theselected space.

In an embodiment, the control unit is configured to construct at leastone three-dimensional image frame of the space, during the given phase,based on image frames acquired at the time when at least some of thecontrast agent is present within the space.

In an embodiment, the apparatus further includes a medical toolconfigured to be inserted into the space, the apparatus is configured toacquire an image of the tool while the tool is inside the space, and thedisplay is configured to display the image of the tool overlaid on theimage frame of the space.

In an embodiment, the control unit is configured to identify when theinjection tool injects the contrast agent by image processing a set ofimage frames of the space.

In an embodiment, the control unit is configured to identify when theinjection tool injects the contrast agent by specifically analyzing aregion of at least some of the plurality of image frames thatcorresponds to a vicinity of a distal tip of the injection tool.

In an embodiment, the control unit is configured to identify when theinjection tool injects the contrast agent by determining a level ofdarkness of the region of at least some of the plurality of image framesthat corresponds to the vicinity of the distal tip of the injectiontool.

In an embodiment, the apparatus further includes a user interface, andthe display is configured to receive an input from a user, via the userinterface, and to display a marking at a given position within theportion of the subject's body within the stabilized set of image frames,in response to the input.

In an embodiment, the display is configured to display two or more viewsof the stabilized set of image frames of the portion of the subject'sbody, and to display the marking at the given position within respectiveviews of the stabilized set of image frames.

In an embodiment, the imaging device is further configured to image aplurality of images of a medical tool disposed within the portion of thesubject's body, and the control unit is configured to generate astabilized set of image frames of the medical tool.

In an embodiment, the medical tool includes a medical tool that isimplanted within the portion of the subject's body, and the imagingdevice is configured to image a plurality of images of the implantedmedical tool.

In an embodiment, the medical tool includes a medical tool that istransiently inserted within the portion of the subject's body, and theimaging device is configured to image a plurality of images of themedical tool while it is inserted within the portion.

In an embodiment, the control unit is configured to enhance thestabilized set of image frames of the medical tool by image processingthe stabilized set of image frames of the medical tool.

In an embodiment, the control unit is configured to determine aphysiological parameter of the subject by analyzing the stabilized setof image frames.

In an embodiment, the control unit is configured to determine aparameter relating to cardiac function of the subject by analyzing thestabilized set of image frames.

In an embodiment, the control unit is configured to determine aparameter relating to respiratory function of the subject by analyzingthe stabilized set of image frames.

In an embodiment, in generating the stabilized set of image frames, thecontrol unit is configured to smoothen a transition between successiveframes of the set of frames.

In an embodiment, the control unit is configured to smoothen thetransition between the successive frames, by:

determining a characteristic of motion of an object within thestabilized set of image frames by image processing frames of thestabilized set of image frames,

generating a simulated image of the object by assuming that the objectcontinues to move according to the determined profile, and

using the simulated image of the object as an intermediate image betweensuccessive image frames.

In an embodiment, the control unit is configured to smoothen thetransition between the successive frames, by:

determining a position of an object within a non-gated image frame thatwas acquired subsequent to a first gated image frame and before a secondgated image frame, and

generating a representation of the object within the stabilized set ofimage frames before the second gated image frame is generated within thestabilized set of image frames.

In an embodiment, the control unit is configured to determine adimension of a region within the portion of the subject's body, byanalyzing the stabilized set of image frames.

In an embodiment, the control unit is configured to output an indicationof a size of a medical tool relative to the region within the portion ofthe subject's body.

In an embodiment,

the apparatus further includes a medical tool configured to be insertedinto the portion of the subject's body and having a known dimension, andthe control unit is configured to determine the dimension of the regionby comparing a dimension of the tool within the stabilized set of imageframes to the known dimension.

In an embodiment, the medical tool includes markers, the markers beingseparated from each other by a known distance, and the control unit isconfigured to determine an orientation at which the medical tool isdisposed within the portion of the subject's body by determining adistance between the markers as viewed within the stabilized set ofimage frames with respect to the known distance.

In an embodiment, the control unit is configured to generate a simulatedimage of a virtual medical tool disposed at the orientation within thestabilized set of image frames of the portion of the subject's body, inresponse to the determining of the distance.

In an embodiment, the apparatus further includes a user interface, andthe control unit is configured to receive an input from a user, via theuser interface, and to generate a simulated image of a virtual medicaltool disposed within the stabilized set of image frames of the portionof the subject's body, in response to receiving the input.

In an embodiment, the control unit is configured to output dimensions ofa real medical tool that corresponds to the simulated image of thevirtual medical tool.

In an embodiment, the control unit is configured to output thedimensions of the real medical tool by accounting for an orientation atwhich the virtual medical tool is disposed within the simulated image.

In an embodiment, the control unit is configured to output thedimensions of the real medical tool by accounting for a curvature of aregion of the portion of the subject's body within which region thevirtual medical tool is disposed within the simulated image.

In an embodiment, the control unit is configured to receive a first anda second input from the user and to generate respective simulated imagesof first and second medical tools being placed within the stabilized setof image frames of the portion of the subject's body, in response toreceiving the inputs.

In an embodiment, the imaging device includes two or more imagingdevices, and the control unit is configured to generate two or morestabilized sets of image frames of the portion of the subject's body,the sets of image frames having been imaged by respective imagingdevices of the two or more imaging devices.

In an embodiment, a first imaging device of the two or more imagingdevices is configured to image the portion of the subject's body beforea medical procedure, a second imaging device of the two or more imagingdevices is configured to image the portion of the subject's body duringthe medical procedure, and the control unit is configured to generatethe stabilized sets of image frames during the medical procedure.

In an embodiment, a first imaging device of the two or more imagingdevices is configured to image the portion of the subject's body fromoutside the portion of the subject's body, and a second imaging deviceof the two or more imaging devices is configured to image regions withinthe portion of the subject's body while the second imaging device isdisposed at respective locations within the portion of the subject'sbody.

In an embodiment, the control unit is configured to associate (a)locations within the stabilized image frames acquired by the firstimaging device that correspond to the respective locations of the secondimaging device, with (b) respective image frames acquired by the secondimaging device while the second imaging device was disposed at therespective locations.

In an embodiment, the apparatus further includes a medical toolconfigured to be inserted into the portion of the subject's body to avicinity of the respective locations while the second imaging device isnot disposed at the respective locations, and the control unit isconfigured to generate (a) respective image frames acquired by thesecond imaging device while the second imaging device was disposed atthe respective locations, when (b) the medical tool is disposed in avicinity of the respective locations.

In an embodiment, the first imaging device includes a fluoroscope andthe second imaging device includes an intravascular ultrasound probe.

In an embodiment, the first imaging device includes a CT scanner and thesecond imaging device includes an intravascular ultrasound probe.

In an embodiment, the first imaging device is configured to acquire theplurality of image frames before the second imaging device images theregions within the portion of the subject's body.

In an embodiment, the first imaging device is configured to acquire theplurality of image frames while the second imaging device images theregions within the portion of the subject's body, and the first imagingdevice is configured to acquire the plurality of image frames byacquiring a plurality of image frames of the second imaging devicedisposed within the portion.

In an embodiment,

the stabilized set of image frames defines a first stabilized set ofimage frames, and

the control unit is configured to generate an additional stabilized setof image frames of the portion of the subject's body,

-   -   by identifying a further given phase of the cyclic activity of        the first body system, and generating an additional set of the        image frames corresponding to image frames of the portion        acquired during the further given phase, and    -   by image tracking at least some of the additional set of image        frames to reduce imaged motion of the portion of the subject's        body associated with the additional motion.

In an embodiment, the given phase includes a systolic phase of a cardiaccycle of the subject and the further given phase includes a diastolicphase of the subject's cardiac cycle, and the control unit is configuredto generate sets of image frames which are stabilized respectively tothe systolic and to the diastolic phases of the subject's cardiac cycle.

In an embodiment, the apparatus further includes a user interface, andthe control unit is configured to receive an input from a user, via theuser interface, and to generate simulated images of a virtual medicaltool disposed within the stabilized sets of image frames of the portionof the subject's body at the given phase and at the further given phase,in response to receiving the input.

In an embodiment, the apparatus further includes a medical tool disposedwithin the portion of the subject's body, and the control unit isconfigured to generate stabilized images of the medical tool disposedwithin the portion of the subject's body respectively at the given phaseand at the further given phase.

In an embodiment, the control unit is configured to determine aphysiological parameter of the subject by comparing the additionalstabilized set of image frames to the first stabilized set of imageframes.

In an embodiment, the control unit is configured to determine aparameter relating to cardiac function of the subject by comparing theadditional stabilized set of image frames to the first stabilized set ofimage frames.

In an embodiment, the control unit is configured to determine aparameter relating to respiratory function of the subject by comparingthe additional stabilized set of image frames to the first stabilizedset of image frames.

In an embodiment, the cyclic activity includes a cardiac cycle of thesubject, and the sensor includes a sensor for sensing a phase of thesubject's cardiac cycle.

In an embodiment, the given phase includes an end-diastolic phase of thesubject's cardiac cycle, and the control unit is configured to generatea stabilized set of the image frames corresponding to image frames ofthe portion acquired during the end-diastolic phase of the subject'scardiac cycle.

In an embodiment, the sensor includes a blood pressure sensor.

In an embodiment, the sensor includes an ECG sensor.

In an embodiment, the sensor includes an image processor configured tosense a phase of the subject's cardiac cycle by comparing image framesof the plurality of image frames to at least one of the image frames ofthe plurality of image frames.

In an embodiment, the cyclic activity includes a respiratory cycle ofthe subject, and the sensor includes a sensor for sensing a phase of thesubject's respiratory cycle.

In an embodiment, the sensor includes an image processor configured tosense a phase of the subject's respiratory cycle by comparing imageframes of the plurality of image frames to at least one of the imageframes of the plurality of image frames.

In an embodiment, the additional motion is a result of cyclic activityof a second body system of the subject, and the control unit isconfigured to reduce imaged motion of the portion of the subject's bodyassociated with the cyclic activity of the second body system by imagetracking at least the set of image frames.

In an embodiment,

the cyclic activity of the first body system has a greater frequencythan the cyclic activity of the second body system, and

the control unit is configured to generate the stabilized set of imageframes of the portion of the subject's body:

-   -   by identifying the given phase of the cyclic activity of the        first body system, and outputting the set of the image frames        corresponding to image frames of the portion acquired during the        given phase, and    -   by image tracking at least the set of image frames to reduce        imaged motion of the portion of the subject's body associated        with the cyclic activity of the second body system.

In an embodiment,

the cyclic activity of the first body system has a lower frequency thana frequency of the cyclic activity of the second body system, and

the control unit is configured to generate the stabilized set of imageframes of the portion of the subject's body:

-   -   by identifying the given phase of the cyclic activity of the        first body system, and outputting the set of the image frames        corresponding to image frames of the portion acquired during the        given phase, and    -   by image tracking at least the set of image frames to reduce        imaged motion of the portion of the subject's body associated        with the cyclic activity of the second body system.

In an embodiment,

the cyclic activity of the first body system includes a cardiac cycle ofthe subject,

the cyclic activity of the second body system includes a respiratorycycle of the subject, and

the control unit is configured to generate the stabilized set of imageframes of the portion of the subject's body:

-   -   by identifying the given phase of the cardiac cycle, and        outputting the set of the image frames corresponding to image        frames of the portion acquired during the given phase, and    -   by image tracking at least the set of image frames to reduce        imaged motion of the portion of the subject's body associated        with the respiratory cycle.

In an embodiment,

the cyclic activity of the first body system includes a respiratorycycle of the subject,

the cyclic activity of the second body system includes a cardiac cycleof the subject, and

the control unit is configured to generate the stabilized set of imageframes of the portion of the subject's body:

-   -   by identifying the given phase of the respiratory cycle, and        outputting the set of the image frames corresponding to image        frames of the portion acquired during the given phase, and    -   by image tracking at least the set of image frames to reduce        imaged motion of the portion of the subject's body associated        with the cardiac cycle.

There is additionally provided, in accordance with an embodiment of theinvention, apparatus for imaging a portion of a body of a subject thatmoves as a result of cyclic activity of a first body system of thesubject and that also undergoes additional motion, and for use with animaging device for acquiring a plurality of image frames of the portionof the subject's body, a sensor for sensing a phase of the cyclicactivity of the first body system, and a display configured to displayimage frames of the portion of the subject's body, the apparatusincluding:

a control unit configured to generate a stabilized set of image framesof the portion of the subject's body:

-   -   by identifying a given phase of the cyclic activity of the first        body system, and outputting a set of the image frames        corresponding to image frames of the portion acquired during the        given phase,    -   by image tracking at least the set of image frames to reduce        imaged motion of the portion of the subject's body associated        with the additional motion,

wherein the control unit is configured to output the stabilized set ofimage frames to be displayed on the display.

There is further provided, in accordance with an embodiment of theinvention, apparatus for imaging a portion of a body of a subject thatmoves as a result of cardiac cyclic activity of the subject and thatalso undergoes additional motion that is at least partially a result ofa respiratory cycle of the subject, the apparatus including:

an imaging device for acquiring a plurality of image frames of theportion of the subject's body;

a sensor for sensing a phase of the cardiac cyclic activity;

a control unit configured to generate a stabilized set of image framesof the portion of the subject's body:

-   -   by identifying a given phase of the cardiac cyclic activity, and        outputting a set of the image frames corresponding to image        frames of the portion acquired during the given phase, and    -   by image tracking at least the set of image frames to reduce        imaged motion of the portion of the subject's body associated        with the additional motion; and

a display configured to display the stabilized set of image frames ofthe portion of the subject's body.

There is additionally provided, in accordance with an embodiment of theinvention, apparatus for use with a portion of a body of a subject thatmoves as a result of cyclic activity of a body system of the subject,the apparatus including:

a sensor for sensing a phase of the cyclic activity;

a medical tool configured to perform a function with respect to theportion of the subject's body; and

a control unit configured:

-   -   in a first cycle of the cyclic activity, to move at least a        portion of the tool in a given direction, in response to the        sensor sensing that the cyclic activity is at a first given        phase thereof,    -   following the given phase in the first cycle and prior to an        occurrence of the given phase in a subsequent cycle of the        cyclic activity, to inhibit the movement of the at least a        portion of the tool, and    -   in a second cycle of the cyclic activity, subsequent to the        inhibiting of the movement, to move the at least a portion of        the tool in the given direction, in response to the sensor        sensing that the second cycle of the cyclic activity is at the        given phase thereof,    -   without moving the at least a portion of the tool in a direction        opposite to the given direction, between (a) moving the at least        a portion of the tool in the given direction in the first cycle,        and (b) moving the at least a portion of the tool in the given        direction in the second cycle.

In an embodiment, the control unit is configured to move a center of thetool by moving the portion of the tool in the given direction.

In an embodiment, the tool includes a tool configured to be controlledremotely by a user.

In an embodiment, the control unit is configured to be reversiblycoupled to the tool.

In an embodiment, the control unit is integrated into the tool.

In an embodiment, the tool includes a guidewire configured to be movedwithin the portion of the subject's body.

In an embodiment, the tool is configured to penetrate an occlusion of alumen of the portion of the subject's body by being advanced through thelumen.

In an embodiment, the tool includes a valve configured to be implantedwithin the portion of the subject's body by being expanded within theportion, and the control unit is configured to move at least a portionof the valve in the given direction, by moving the at least the portionof the valve in an expansion-related direction.

In an embodiment, the tool includes a septal-closure device configuredto be implanted within the portion of the subject's body by beingexpanded within the portion, and the control unit is configured to moveat least a portion of the septal-closure device in the given direction,by moving the at least the portion of the septal-closure device in anexpansion-related direction.

In an embodiment, the cyclic activity includes a respiratory cycle ofthe subject, and the sensor is configured to sense a phase of therespiratory cycle.

In an embodiment, the sensor includes an image processor configured tosense a phase of the subject's respiratory cycle by comparing imageframes of a plurality of image frames of the portion of the subject'sbody to at least one of the image frames of the plurality of imageframes.

In an embodiment, the cyclic activity includes a cardiac cycle of thesubject, and the sensor is configured to sense a phase of the cardiaccycle.

In an embodiment, the sensor includes a blood pressure sensor.

In an embodiment, the sensor includes an image processor configured tosense a phase of the subject's cardiac cycle, by comparing image framesof the plurality of image frames to at least one of the image frames ofthe plurality of image frames.

In an embodiment, the sensor includes an ECG sensor configured to sensea phase of the cardiac cycle by detecting an ECG signal of the subject.

In an embodiment, the tool includes a balloon configured to be inflatedinside a lumen of the portion of the subject's body, and the controlunit is configured to move at least a portion of the balloon in thegiven direction, by moving a surface of the balloon in aninflation-related direction.

In an embodiment, the control unit is configured to inflate the ballooncontinuously for a period of time prior to the first cycle of the cyclicactivity.

In an embodiment, the control unit is configured to inflate the ballooncontinuously for a period of time subsequent to the second cycle of thecyclic activity.

In an embodiment, the apparatus further includes a stent, and the stentis configured to be positioned against a wall of the lumen via theinflation of the balloon.

In an embodiment, the apparatus further includes a valve disposed on thesurface of the balloon, and the valve is configured to be expanded viathe inflation of the balloon.

In an embodiment, the apparatus further includes a valve configured tocontrol flow to the balloon, and the control unit is configured toregulate movement of the surface of the balloon in the inflation-relateddirection by controlling the valve.

In an embodiment, the apparatus further includes a tube configured tosupply fluid to the balloon, the apparatus further includes one or moresqueezing surfaces that are disposed around the tube, and the controlunit is configured to inhibit movement of the surface of the balloon inthe inflation-related direction by driving a current that causes thesqueezing surfaces to squeeze together.

In an embodiment, the cyclic activity includes a cardiac cycle of thesubject, the portion of the subject's body includes a portion of acardiovascular system of the subject that moves as a result of thesubject's cardiac cycle, and the balloon is configured to be inflatedinside the portion of the cardiovascular system.

In an embodiment, the given phase of the cardiac cycle includesend-diastole, and the control unit is configured to move the surface ofthe balloon in the inflation-related direction in response to the sensorsensing end-diastole.

In an embodiment, the apparatus further includes an instrumentconfigured to be operated by a user, and the control unit is configuredto move the portion of the tool in the given direction, (a) in responseto the sensor sensing that the cyclic activity is at the given phasethereof, and (b) in response to the instrument being operated by theuser.

In an embodiment, the instrument is configured to provide force feedbackto the user that is independent of the cyclic activity.

In an embodiment, the instrument is configured to provide force feedbackto the user that is smoothened with respect to the cyclic activity.

In an embodiment, the tool includes a tubular structure configured tobypass an occlusion of a blood vessel within the portion of thesubject's body.

In an embodiment, the tubular structure includes a blood vessel graft.

In an embodiment, the control unit is configured to move the tubularstructure in the given direction by moving a distal end of the structurein a direction from (a) within the blood vessel on a proximal side ofthe occlusion, to (b) outside the blood vessel.

In an embodiment, the control unit is configured to move the tubularstructure in the given direction by moving a distal end of the structurein a direction from (a) outside the blood vessel, to (b) within theblood vessel on a distal side of the occlusion.

There is further provided, in accordance with an embodiment of theinvention, apparatus for use with a portion of a body of a subject thatmoves as a result of cyclic activity of a body system of the subject,the apparatus including:

a sensor for sensing a phase of the cyclic activity;

a medical tool configured to mechanically perform an action during asingle cycle of the cyclic activity with respect to the portion of thesubject's body; and

a control unit configured to actuate the tool to mechanically performthe action in response to the sensor sensing that the cyclic activity isat a given phase thereof.

In an embodiment, the tool includes a balloon configured to appositionitself to a lumen of the portion of the subject's body during the singlecycle by being inflated in response to the sensor sensing that thecyclic activity is at the given phase thereof.

In an embodiment, the balloon is configured to be inflated continuouslyfor a period of time prior to the balloon appositioning itself to thelumen by being inflated during the single cycle.

In an embodiment, the balloon is configured to be inflated continuouslyfor a period of time subsequent to the balloon appositioning itself tothe lumen by being inflated during the single cycle.

In an embodiment, the tool includes a stent configured to appositionitself to a lumen of the portion of the subject's body by being expandedinside the lumen of the portion of the subject's body during a singlecycle of the cyclic activity, in response to the sensor sensing that thecyclic activity is at the given phase thereof.

In an embodiment, the stent includes a self-expansible portionconfigured to self-expand inside the lumen of the portion of thesubject's body.

In an embodiment, the tool includes a valve configured to be implantedwithin the portion of the subject's body by mechanically expandingwithin the portion, and the control unit is configured to actuate thevalve to expand in response to the sensor sensing that the cyclicactivity is at the given phase thereof.

In an embodiment, the cyclic activity includes a cardiac cycle of thesubject, and the control unit is configured to actuate the valve toexpand in response to the sensor sensing that the cardiac cycle is atthe given phase thereof.

In an embodiment, the given phase includes an end-diastolic phase of thecardiac cycle, and the control unit is configured to actuate the valveto expand in response to the sensor sensing the end-diastolic phase ofthe cardiac cycle.

In an embodiment, the tool includes a septal-closure device configuredto be implanted within a heart of the subject by mechanically expandingwithin the heart, and the control unit is configured to actuate theseptal-closure device to expand in response to the sensor sensing thatcardiac cyclic activity of the subject is at a given phase thereof.

In an embodiment, the given phase includes an end-diastolic phase of thecardiac cycle, and the control unit is configured to actuate theseptal-closure device to expand in response to the sensor sensing theend-diastolic phase of the cardiac cycle.

There is further provided, in accordance with an embodiment of theinvention, apparatus for use with a portion of a subject's body thatundergoes neural cyclic activity, the apparatus including:

a sensor for sensing a phase of the neural cyclic activity;

a medical tool configured to perform a function with respect to theportion of the subject's body; and

a control unit configured to actuate the tool to perform the function,in response to the sensor sensing that the cyclic activity is at a givenphase thereof.

There is additionally provided, in accordance with an embodiment of thepresent invention, apparatus for use with a portion of a body of asubject that moves as a result of cyclic activity of a body system ofthe subject, and for use with a sensor for sensing a phase of the cyclicactivity, and for use with a medical tool configured to perform afunction with respect to the portion of the subject's body, theapparatus including:

a control unit configured:

-   -   in a first cycle of the cyclic activity, to move at least a        portion of the tool in a given direction, in response to the        sensor sensing that the cyclic activity is at a given phase        thereof,    -   following the given phase in the first cycle and prior to an        occurrence of the given phase in a subsequent cycle of the        cyclic activity, to inhibit the movement of the at least a        portion of the tool, and    -   in a second cycle of the cyclic activity, subsequent to the        inhibiting of the movement, to move the at least a portion of        the tool in the given direction, in response to the sensor        sensing that the second cycle of the cyclic activity is at the        given phase thereof,    -   without moving the at least a portion of the tool in a direction        opposite to the given direction, between (a) moving the at least        a portion of the tool in the given direction in the first cycle,        and (b) moving the at least a portion of the tool in the given        direction in the second cycle.

There is further provided, in accordance with an embodiment of theinvention, apparatus for use with a portion of a body of a subject thatmoves as a result of cyclic activity of a body system of the subject,the apparatus including:

a sensor for sensing a phase of the cyclic activity;

a medical tool configured to perform a function with respect to theportion of the subject's body; and

a control unit configured:

-   -   in a first cycle of the cyclic activity in response to the        sensor sensing that the cyclic activity is at a first given        phase thereof, to move the tool,    -   in a subsequent cycle of the cyclic activity in response to the        sensor sensing that the cyclic activity is at the given phase        thereof, to actuate the tool to execute an action selected from        the group consisting of: performing the function and moving,    -   following the given phase in the subsequent cycle and prior to        an occurrence of the given phase in a further subsequent cycle        of the cyclic activity, to inhibit the selected action of the        tool, and    -   in the further subsequent cycle of the cyclic activity,        subsequent to the inhibiting of the action, and in response to        the sensor sensing that the further subsequent cycle of the        cyclic activity is at the given phase thereof, to actuate the        tool to execute an action selected from the group.

In an embodiment, the tool includes a myocardial revascularization toolconfigured to sequentially apply a revascularization treatment torespective treatment sites within the portion of the subject's body, andthe control unit is configured to:

actuate the tool to perform the function by actuating the tool to applya revascularization treatment to a treatment site, and

to move the tool by moving at least a portion of the revascularizationtool toward successive treatment sites.

In an embodiment, the control unit is configured to move the tool bymoving the tool to create a defined pattern of treatment sites.

In an embodiment, the tool includes an ablation tool configured tosequentially ablate respective ablation sites within the portion of thesubject's body, and the control unit is configured to:

actuate the tool to perform the function by actuating the tool to ablatean ablation site, and

-   -   to move the tool by moving at least a portion of the ablation        tool toward successive ablation sites.

In an embodiment, the ablation tool is configured to ablate the ablationsites using an ablation technique selected from the group consisting of:laser ablation, electrocautery, RF ablation, cryogenic ablation, andultrasound ablation.

In an embodiment, the control unit is configured to move the at leastthe portion of the tool by moving the at least the portion of the toolto create a defined pattern of ablation sites.

In an embodiment, the control unit is configured to apply a Mazeprocedure to the ablation sites by moving the at least the portion ofthe tool toward successive ablation sites.

In an embodiment, the ablation tool is configured to apply a pulmonaryvein isolation technique to a heart of the subject by moving the atleast the portion of the tool toward successive isolation sites.

In an embodiment, the tool includes an injection tool, configured toinject a substance within the portion of the subject's body, and thecontrol unit is configured to:

-   -   actuate the tool to perform the function by actuating the tool        to inject the substance, and    -   to move the tool by moving at least a portion of the tool toward        an injection site.

In an embodiment, the substance includes DNA molecules, and theinjection tool is configured to inject the DNA molecules into hearttissue of the subject.

In an embodiment, the substance includes stem cells, and the injectiontool is configured to inject the stem cells into heart tissue of thesubject.

In an embodiment, the tool includes a needle configured to suture tissuewithin the portion of the subject's body, and the control unit isconfigured to:

-   -   actuate the tool to perform the function by actuating the tool        to suture the tissue, and    -   to move the tool by moving the needle toward successive suturing        sites.

In an embodiment, the tissue includes tissue of the subject selectedfrom the group consisting of cardiac tissue and coronary tissue, and theneedle is configured to suture the selected tissue.

In an embodiment, the tool includes a needle configured to aspiratetissue from an aspiration site within the portion of the subject's body,and the control unit is configured to:

actuate the needle to perform the function by actuating the needle toaspirate the tissue, and move the needle by moving the needle toward theaspiration site.

In an embodiment, the needle is configured to perform trans-thoracicneedle aspiration.

In an embodiment, the needle is configured to perform trans-bronchialneedle aspiration.

There is additionally provided, in accordance with an embodiment of theinvention, apparatus for opening an at least partial occlusion of alumen of a subject's body, the apparatus including:

a sensor for sensing a phase of the cyclic activity;

an occlusion-opening tool configured to open the occlusion; and

a control unit configured:

-   -   in a first cycle of the cyclic activity in response to the        sensor sensing that the cyclic activity is at a first given        phase thereof, to actuate the tool to perform an        occlusion-opening action,    -   following the given phase in the first cycle and prior to an        occurrence of the given phase in a subsequent cycle of the        cyclic activity, to inhibit the action of the tool, and    -   in a second cycle of the cyclic activity, subsequent to the        inhibiting of the action, and in response to the sensor sensing        that the second cycle of the cyclic activity is at the given        phase, to actuate the tool to perform the action.

In an embodiment, after actuating the tool at the given phase of thefirst cycle and before the actuation of the tool at the given phase ofthe subsequent cycle, the control unit is configured to retract the toolfrom the occlusion.

In an embodiment, the occlusion-opening tool includes a tool configuredto open the occlusion by directing acoustic waves toward the occlusion.

There is further provided, in accordance with an embodiment of theinvention, apparatus for use with a portion of a body of a subject thatmoves as a result of cyclic activity of a body system of the subject,the apparatus including:

an imaging device for acquiring a plurality of image frames of theportion of the subject's body;

a sensor for sensing a phase of the cyclic activity;

a medical tool configured to perform a function with respect to theportion of the subject's body;

a control unit configured to:

-   -   generate a stabilized set of image frames of the medical tool        disposed within the portion of the subject's body,    -   actuate the tool to execute an action selected from the group        consisting of performing the function and moving, in response to        the sensor sensing that the cyclic activity is at a given phase        thereof, and    -   inhibit the tool from executing the action in response to the        sensor sensing that the cyclic activity is not at the given        phase; and

a display configured to facilitate use of the tool by displaying thestabilized set of image frames of the medical tool disposed within theportion of the subject's body.

In an embodiment, the apparatus further includes a user interface, andthe control unit is configured to receive an input from a user, via theuser interface, and to designate the given phase in response to theinput.

In an embodiment, the tool includes a valve configured to be implantedwithin the portion of the subject's body by being expanded within theportion, and the control unit is configured to actuate the valve byexpanding the valve.

In an embodiment, the tool includes a septal-closure device configuredto be implanted within the portion of the subject's body by beingexpanded within the portion, and the control unit is configured toactuate the septal-closure device by expanding the septal closuredevice.

In an embodiment, the tool includes a balloon configured to perform thefunction by being inflated inside a lumen of the portion of thesubject's body.

In an embodiment, the tool includes a tubular structure configured tobypass an occlusion of a blood vessel within the portion of thesubject's body.

In an embodiment, the tool includes a myocardial revascularization toolconfigured to sequentially apply a revascularization treatment torespective treatment sites within the portion of the subject's body, andthe control unit is configured to:

actuate the tool to perform the function by actuating the tool to applya revascularization treatment to a treatment site, and

move the tool by moving at least a portion of the revascularization tooltoward successive treatment sites.

In an embodiment, the tool includes an ablation tool configured tosequentially ablate respective ablation sites within the portion of thesubject's body, and the control unit is configured to:

actuate the tool to perform the function by actuating the tool to ablatean ablation site, and

move the tool by moving at least a portion of the ablation tool towardsuccessive ablation sites.

In an embodiment, the tool includes an injection tool configured toinject a substance within the portion of the subject's body and thecontrol unit is configured to:

actuate the tool to perform the function by actuating the tool to injectthe substance, and

move the tool by moving at least a portion of the tool toward aninjection site.

In an embodiment, the tool includes a needle configured to suture tissuewithin the portion of the subject's body, and the control unit isconfigured to:

actuate the tool to perform the function by actuating the tool to suturethe tissue, and

move the tool by moving the needle toward successive suturing sites.

In an embodiment, the tool includes a needle configured to aspiratetissue from an aspiration site within the portion of the subject's body,and the control unit is configured to:

actuate the needle to perform the function by actuating the needle toaspirate the tissue, and

move the needle by moving the needle toward the aspiration site.

In an embodiment, the tool includes an occlusion-opening tool configuredto perform the function by performing an occlusion-opening action on anat least partial occlusion of a lumen of the portion of the subject'sbody.

In an embodiment, the tool is configured to perform theocclusion-opening action by moving toward the occlusion, and afteractuating the tool at the given phase of a first cycle and before theactuation of the tool at the given phase of a subsequent cycle, thecontrol unit is configured to retract the tool from the occlusion.

In an embodiment, the control unit is configured to generate thestabilized set of image frames by image tracking at least some of theplurality of image frames to reduce imaged motion of the portion of thesubject's body associated with the cyclic activity.

In an embodiment, the control unit is configured to generate thestabilized set of image frames by generating a set of tracked imageframes corresponding to image frames of the portion acquired during thegiven phase.

In an embodiment, the control unit is configured to generate thestabilized set of image frames by generating a set of the image framescorresponding to image frames of the portion acquired during the givenphase.

In an embodiment, the control unit is configured to reduce imaged motionof the portion of the subject's body associated with motion of theportion of the subject's body by image tracking the set of image frames.

In an embodiment, the control unit is configured to generate the set ofimage frames corresponding to image frames of the portion acquiredduring the given phase, by actuating the imaging device to acquire theplurality of image frames only when the cyclic activity is at the givenphase.

In an embodiment, the imaging device is configured to acquire theplurality of image frames throughout the cyclic activity, and thecontrol unit is configured to generate the set of image framescorresponding to image frames of the portion acquired during the givenphase by selecting image frames corresponding to image frames of theportion acquired during the given phase from the plurality of imageframes.

In an embodiment, the control unit is configured to generate anadditional stabilized set of image frames of the portion of thesubject's body, by identifying a further given phase of the cyclicactivity of the body system, and generating a set of the image framescorresponding to image frames of the portion acquired during the furthergiven phase.

In an embodiment, the cyclic activity includes a cardiac cycle of thesubject, and the sensor includes a sensor for sensing a phase of thesubject's cardiac cycle.

In an embodiment, the given phase includes an end-diastolic phase of thesubject's cardiac cycle, and the control unit is configured to generatea stabilized set of the image frames corresponding to image frames ofthe portion acquired during the end-diastolic phase of the subject'scardiac cycle.

In an embodiment, the sensor includes an image processor configured tosense movement of the portion of the subject's body by comparing imageframes of the plurality of image frames to at least one of the pluralityof image frames.

In an embodiment, the cyclic activity includes a respiratory cycle ofthe subject, and the sensor includes a sensor for sensing a phase of thesubject's respiratory cycle.

In an embodiment, the sensor includes an image processor configured tosense movement of the portion of the subject's body by comparing imageframes of the plurality of image frames to at least one of the pluralityof image frames.

In an embodiment, the apparatus further includes an instrumentconfigured to be operated by a user, and the control unit is configuredto actuate the tool to perform the function, (a) in response to thesensor sensing that the cyclic activity is at the given phase thereof,and (b) in response to the instrument being operated by the user.

In an embodiment, the instrument is configured to provide force feedbackto the user that is independent of the cyclic activity.

In an embodiment, the instrument is configured to provide force feedbackto the user that is smoothened with respect to the cyclic activity.

There is further provided, in accordance with an embodiment of theinvention, apparatus for use with a portion of a body of a subject thatmoves as a result of cyclic activity of a body system of the subject,and for use with an imaging device for acquiring a plurality of imageframes of the portion of the subject's body, a sensor for sensing aphase of the cyclic activity, a medical tool configured to perform afunction with respect to the portion of the subject's body, and adisplay configured to facilitate use of the tool by displaying imageframes of the portion of the subject's body, the apparatus including:

a control unit configured to:

-   -   generate a stabilized set of image frames of the portion of the        subject's body,    -   output the stabilized set of image frames to the display,    -   actuate the tool to perform the function in response to the        sensor sensing that the cyclic activity is at a given phase of        the cyclic activity, and    -   inhibit the tool from performing the function in response to the        sensor sensing that the cyclic activity is not at the given        phase.

There is additionally provided, in accordance with an embodiment of thepresent invention, apparatus for use with a portion of a body of asubject that moves as a result of cyclic activity of a body system ofthe subject, the apparatus including:

an imaging device for acquiring a plurality of image frames of theportion of the subject's body;

a sensor for sensing a phase of the cyclic activity;

a medical tool configured to mechanically perform an action during asingle cycle of the cyclic activity with respect to the portion of thesubject's body; and

a control unit configured to:

-   -   generate a stabilized set of image frames of the portion of the        subject's body, and    -   actuate the tool to mechanically perform the action in response        to the sensor sensing that the cyclic activity is at a given        phase thereof.

In an embodiment, the control unit is configured to generate thestabilized set of image frames by generating a set of image frames thatare stabilized with respect to the given phase of the cyclic activity.

In an embodiment, the tool includes a balloon configured to appositionitself to a lumen of the portion of the subject's body during a singlecycle by being inflated, in response to the sensor sensing that thecyclic activity is at the given phase thereof.

In an embodiment, the tool includes a stent configured to be implantedby being expanded inside a lumen of the portion of the subject's bodyduring a single cycle of the cyclic activity, in response to the sensorsensing that the cyclic activity is at the given phase thereof.

In an embodiment, the tool includes a valve configured to be implantedwithin the portion of the subject's body by mechanically expandingwithin the portion during a single cycle of the cyclic activity, inresponse to the sensor sensing that the cyclic activity is at the givenphase thereof.

In an embodiment, the tool includes a septal-closure device configuredto be implanted within a heart of the subject by mechanically expandingwithin the heart during a single cycle of cardiac cyclic activity of thesubject, in response to the sensor sensing that the cyclic activity isat the given phase thereof.

The present invention will be more fully understood from the followingdetailed description of embodiments thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of apparatus for generating astabilized image of a portion of a subject's body, in accordance with anembodiment of the present invention;

FIG. 2 is a schematic illustration of a heart at various phases of thecardiac cycle alongside an ECG signal associated with the cardiac cycle;

FIG. 3 is a schematic illustration of image frames of a subject's heartbeing gated to a phase of a physiological cycle, in accordance with anembodiment of the present invention;

FIG. 4 is a schematic illustration of image frames of a subject's heartbeing image tracked, in accordance with an embodiment of the presentinvention;

FIG. 5 is a schematic illustration of image frames of a subject's heartbeing (a) gated to a phase of a physiological cycle, and (b) imagetracked, in accordance with an embodiment of the present invention;

FIG. 6 is a schematic illustration of apparatus for synchronizingactuation of a medical device with a physiological cycle, in accordancewith an embodiment of the present invention;

FIGS. 7A-B are schematic illustrations of the actuation of inflation ofa balloon in synchronization with a physiological cycle, in accordancewith an embodiment of the present invention;

FIG. 7C is a graph schematically showing the pressure of the balloon asa function of time, in accordance with an embodiment of the presentinvention;

FIG. 8 is a schematic illustration of apparatus for facilitating thesynchronized inflation of a balloon, in accordance with an embodiment ofthe present invention;

FIGS. 9-11 are schematic illustrations of apparatus for facilitating thesynchronized inflation of a balloon, in accordance with anotherembodiment of the present invention;

FIG. 12 is a schematic illustration of apparatus for facilitating thesynchronized inflation of a balloon, the apparatus being built into aninflation device, in accordance with a further embodiment of the presentinvention;

FIG. 13 is a schematic illustration of synchronization of thepenetration of an occlusion of a blood vessel with cyclic movement ofthe blood vessel, in accordance with an embodiment of the presentinvention;

FIG. 14 is a schematic illustration of a modulator for synchronizing thepenetration of an occlusion of a blood vessel with the cyclic movementof the blood vessel, in accordance with an embodiment of the presentinvention;

FIG. 15 is a schematic illustration of a handheld actuator thatcomprises the modulator shown in FIG. 14, in accordance with anembodiment of the present invention; and

FIG. 16 is a schematic illustration of the synchronization of atransluminal placement of a coronary bypass graft with the cyclic motionof a portion of the subject's body, in accordance with an embodiment ofthe present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

As used herein:

-   -   The term “physiological signal or process” refers to any        cyclical physiological signal or process in the patient's body        including, but not limited to, ECG, blood pressure (e.g.,        systolic and diastolic), Peripheral Arterial Tone, EEG,        respiration, the shifting/expansion/contraction of an organ,        acquired images in which any of the above signals or processes        may be observed, or any combination, derivation, extrapolation        or manipulation thereof.    -   The terms “medical tool,” “tool” and “probe” mean any type of a        diagnostic or therapeutic or other functional tool including,        but not limited to, a cardiovascular catheter, a stent delivery        and/or placement and/or retrieval tool, a balloon delivery        and/or placement and/or retrieval tool, a valve delivery and/or        placement and/or retrieval tool, a graft delivery and/or        placement and/or retrieval tool, a tool for the delivery and/or        placement and/or retrieval of an implantable device or of parts        of such device, an implantable device or parts thereof, a guide        wire, a suturing tool, a biopsy tool, an aspiration tool, a        navigational tool, a localization tool, a probe comprising one        or more location sensors, a tissue characterization probe, a        probe for the analysis of fluid, a measurement probe, an        electrophysiological probe, a stimulation probe, an ablation        tool, a tool for penetrating or opening partial or total        occlusions in blood vessels, a drug or substance delivery tool,        a chemotherapy tool, a photodynamic therapy tool, a        brachytherapy tool, a local irradiation tool, a laser device, a        tool for delivering energy, a tool for delivering markers or        biomarkers, a tool for delivering biological glue, an irrigation        device, a suction device, a ventilation device, a device for        delivering and/or placing and/or retrieving a lead of an        electrophysiological device, a lead of an electrophysiological        device, a pacing device, an imaging device, a sensing probe, a        probe comprising an optical fiber, a robotic tool, a tool that        is controlled remotely, or any combination thereof.    -   The terms “image” and “imaging” refer to any type of medical        imaging, typically presented as a sequence of images and        including ionizing radiation, non-ionizing radiation, video,        fluoroscopy, angiography, ultrasound, CT, MRI, PET, PET-CT, CT        angiography, SPECT, Gamma camera imaging, Optical Coherence        Tomography (OCT), Vibration Response Imaging (VRI), Optical        Imaging, infrared imaging, electrical mapping imaging, other        forms of Functional Imaging, or any combination or fusion        thereof. Examples of ultrasound imaging include Endo-Bronchial        Ultrasound (EBUS), Trans-Thoracic Echo (TTE), Trans-Esophageal        Echo (TEE), Intra-Vascular Ultrasound (IVUS), Intra-Cardiac        Ultrasound (ICE), etc.    -   The terms “periodic” and “cyclical,” when used in the context of        the motion of a body organ, are interchangeable.    -   The terms “gating” and “synchronization,” and their various        derivations, when used in the context of synchronizing between        an image display and one or more physiological signals or        processes or between the activation of a medical tool and one or        more physiological signals or processes, are interchangeable.        (The term “coherence” has also been known to describe the same.)    -   The terms “stationary” and “stabilized,” when used in the        context of displayed images, mean a display of a series of        images in a manner such that the periodic or cyclical motion of        the body organ(s) being imaged is typically, partially or fully,        reduced or not noticeable to the viewer. Typically, such images        are gated to one or more physiological signals or processes        whose cycle(s) correspond to a motion cycle of the organ being        imaged.    -   The term “virtual stabilization,” when used in reference to a        moving organ, refers to a situation where the displayed images        of said organ are stabilized, partially or fully, with respect        to the motion of the organ, and/or tool(s) applied to the organ        are actuated in synchronization with a selected phase in the        motion of the organ. (Motion of the organ may comprise cyclical        and non-cyclical motion.) Consequently, the moving organ is        typically viewed and/or acted upon as if it is in a situation of        (partial or full) virtual stabilization.    -   The terms “synchronizing” and “gating,” and derivations thereof,        when used in reference to an image stream, describes the        identification and selection of individual image frames from        such image stream, wherein such frames are acquired at a same        selected phase in a plurality of occurrences of a cyclical        physiological signal or process.    -   The term “gating,” and derivations thereof, when used in        reference to a medical tool, describes the movement and/or        application of the tool at a same selected phase in a plurality        of occurrences of a cyclical physiological signal or process.    -   The term “image tracking” is used to describe a process by which        images (including images acquired at different phases in the        motion of an organ) are aligned to one another by means of        aligning among such images one or more features, or regions of        interest, that are observable in most or all images. The term        should be construed to be synonymous with the terms “video        tracking,” “frame tracking,” and “object tracking.”    -   The term “real time,” when used in reference to the application        of virtual stabilization or of an element thereof, means without        a noticeable delay.

The term “near real time,” when used in reference to the application ofvirtual stabilization or of an element thereof, means with a shortnoticeable delay (such as approximately one or two motion cycles of theapplicable organ, and, in the case of procedures relating to organs orvessels the motion of which are primarily as a result of the cardiaccycle, less than 4 seconds).

In some embodiments, apparatus and methods are provided for facilitatingmedical procedures performed on cyclically-moving organs, so that suchprocedures are performed under a partial or full virtual stabilizationof such organs. The virtual stabilization typically comprises twoelements, namely (a) the stabilization of the image(s) of the organ and(b) the synchronization of tool(s) being actuated and/or moved, with themovement of the organ. At least one of these two major elements isapplied.

Examples of organs which move cyclically include, but are not limitedto, the heart, the coronary blood vessels, the aorta, certain otherblood vessels (e.g., renal, carotid), the majority of the respiratorytract, certain parts of the digestive tract (e.g., the stomach, thesmall intestine), certain parts of the thorax (e.g., the diaphragm), theeyes, etc. The description hereinbelow relates mainly to the example ofthe body organ being the heart and/or the coronary blood vessels, andthe physiological signal used for synchronization or gating in suchexamples is typically the ECG. However, the scope of the inventionincludes applying the apparatus and methods described hereinbelow to anyportion of a subject's body that moves as a result of the cyclicactivity of a body-system of the subject.

Reference is now made to FIG. 1, which is a schematic illustration ofapparatus for acquiring image frames of a portion of a subject's heart,in accordance with an embodiment of the present invention. Anangiographic/fluoroscopic camera 11 acquires a plurality of imageframes, throughout the cyclic activity of the heart. When the imageframes are not stabilized, an image or video stream 14 is generated,which is blurred due to the cyclical motion of the imaged heart.

In some embodiments, the apparatus generates a stabilized video stream15 by a gating procedure performed by processor 13 in response to an ECGsignal 12, a blood pressure sensor, a displacement sensor, a vibrationsensor and/or any combinations or derivations thereof, thus yieldingsaid stabilized image or video stream 15. Alternatively or additionally,the image frames are gated with respect to the subject's respiratorycycle. In some embodiments, the subject's respiratory cycle is detectedby means of a respiration sensor, such as a stretch belt, a displacementsensor, a vibration sensor, and/or any combinations or derivationsthereof.

In some embodiments, the aforementioned gating is performed directly inconjunction with the actual expansion and contraction of the heartmuscle in the course of the cardiac cycle, as such expansion process isobserved by the fluoroscopic/angiographic camera, discerning by means ofimage processing the relative distances among identifiable features suchas the coronary blood vessels.

In some embodiments, gating is performed initially with respect to theECG signal, or to another signal corresponding to cardiac motion, and/orto any combination or derivation of signals thereof, but afterwardsgating is performed by means of image processing. For example, an imageframe corresponding to a selected phase in the ECG signal is identifiedand determined to be a “baseline image frame.” After such identificationof a “baseline image frame” has been achieved, gating of the subsequentimage stream is done by means of selecting those image frames where theshape of the observed anatomy is identical, or most similar, to theshape observed in the baseline image frame.

For some applications, the aforementioned gating is applied directly tothe radiation source of the fluoroscopic/angiographic camera, so thatimaging is performed intermittently, e.g., only during or leading up toone or more specific phases in the cardiac cycle at which theacquisition of a (gated) image frame is desired.

Techniques described herein, above or below, may be practiced incombination with techniques described in one or more of the referencescited in the Background section of this application.

The stabilized image frames are typically produced at the rate of thepatient's heart rate. The resulting frame rate is typically one or twoframes per second, which is considered a low-frame rate compared to whatthe human eye interprets as continuous. In some embodiments, a gapfilling technique is applied among the image frames that were selectedfor display by the gating. Additional intermediate image frames aregenerated, thus increasing the visible frame rate, typically smootheningthe transitions among the gated and displayed images and making theimage stream easier to observe. In some embodiments, such gap fillingutilizes image processing methods such as blending, morphing or acombination thereof.

In some embodiments, the gap-filling techniques include a predictivealgorithm that is applied to generate image frames after the most recentgated and displayed image frame, but prior to the next gated anddisplayed image frame. For example, an image processor determines acharacteristic of motion of the tool, based upon previously-acquiredimage frames. The motion profile is extrapolated to generate a simulatedimage frame of the tool by assuming that the tool continues to moveaccording to the determined profile. The simulated image frame is thenused as an intermediate image between successive image frames.

In some embodiments of the gap-filling, visual information from imagesthat were acquired in the original image stream, but are not displayedin the gated image stream, may be used to discern some of the changesthat have occurred since the most recent gated and displayed image.Those changes are then applied to the most recent gated and displayedimage, to generate new image frames ahead of the next gated anddisplayed image. For example, in a beating heart wherein medical toolsare manipulated, such visual information may comprise changes in toolpositions relative to visible anatomical landmarks that move togetherwith the heart. Such changes are then applied to the most recent gatedand displayed image, leading to a representation of the tool beinggenerated and displayed within the stabilized video stream ahead of thenext gated and displayed image frame.

The gap filling described hereinabove is applied by processor 13.Typically, it is applied in the transition between every two consecutivegated image frames. The resulting, stabilized video stream is typicallydisplayed in the course of the procedure, and typically in real time orin near real time.

In some embodiments, the stabilized video stream is stored and isdisplayed subsequent to the procedure in which the image frames areacquired.

In some embodiments, two or more of the streams of images, including theoriginal “jumpy” images and the “smoothened” gated images, are displayedside by side (which may be achieved using two or more separate physicaldisplays, or using two or more software windows within the same physicaldisplay).

In some embodiments, the “smoothened,” gated image stream is displayedin a shared manner on the same display that is used for other purposesin the procedure room, such as on an existing “main” or “reference” or“re-loop” display in a coronary catheterization lab.

Reference is now made to FIG. 2, which is a schematic illustration of aheart at various phases of the cardiac cycle alongside an ECG signalassociated with the cardiac cycle. FIG. 2 illustrates the correspondencebetween triggering points 21, 22 and 23 in the ECG trace and phases 24,25 and 26 in the cardiac cycle. Different points in the ECG tracetypically correspond to different phases in the cardiac cycle. Thevolume and shape of the heart typically vary throughout the cardiaccycle. The displayed images of the pulsating heart may be gated to anyof these points or phases. In some embodiments, the heart may thereforebe continuously viewed at a specific volume and/or shape.

In some embodiments, an operator (e.g., an interventional cardiologist)shifts the phase point to view the cardiac image at any desired phase inthe cycle of the ECG signal, via an input to processor 13 (shown in FIG.1). In some embodiments, the specific phase of the cardiac cycle towhich the displayed images are gated may be changed by the operator inthe course of viewing the images.

In some embodiments, the stabilized video stream is gated specificallyto the end of the diastolic phase of the cardiac cycle. (At theend-diastolic phase the ventricles are typically at their peak volume.)In addition, the inventors hypothesize that the coronary blood vesselsmay be spread apart at the end-diastolic phase of the cardiac cycle,and, for example, in the case of an angioplasty procedure, that may bethe view most desired by a physician. Alternatively the stabilized videostream is gated to a different phase of the subject's cardiac cycle, forexample, systole, or mid-diastole.

In some embodiments, more than one stabilized video stream is displayedconcurrently. For example, a stabilized video stream at a diastolicphase of the cardiac cycle is displayed concurrently with anotherstabilized video stream at a systolic phase of the cardiac cycle.

In some embodiments, the gated images at different phases of the cardiaccycle form a basis for determining a parameter of the subject'scardiovascular system, for example, the ejection fraction of the heart(using image processing techniques known in the art, mutatis mutandis).In some embodiments, image streams are stabilized with respect to two ormore phases of the subject's respiratory cycle, and a parameter of thesubject's respiratory cycle is determined using one, or both of theimage streams, for example, by comparing the image streams to eachother. For example, the subject's tidal volume may be determined bydetermining from the image streams the size of the subject's lungs atthe end of the exhalation phase of the subject's respiratory cycle andthe size of the subject's lungs at the end of the inhalation phase ofthe cycle.

In some embodiments, processor 13 (FIG. 1) stabilizes the image of theportion of the subject's body with respect to additional motion of theportion. Some physiological signals or processes correspond to a changein the shape of the organs being imaged. Other signals or processesmainly correspond to a change in the location of such organs but haveless of a correspondence to their shape. In some cases, signals orprocesses of those two categories apply to a certain organ or organsconcurrently. For example, in the case of the heart and the coronaryblood vessels, those organs typically twist, contract and expand in thecourse of the cardiac cycle (also corresponding to the ECG signal),while at the same time they also typically shift up and down in thecourse of the respiratory cycle. In addition, such organs may shift in anon-cyclical manner due to “whole-body motion” of the subject, forexample, due to the subject coughing or moving on his/her bed.(“Whole-body motion” is to be understood as referring to non-cyclical,noticeable motion of an external portion of the subject's body, even inthe absence of the subject's entire body moving.)

In some embodiments, for the creation of a stabilized video stream ofthe organ(s) being imaged, a cyclical signal or process typicallycorresponding to a change in the shape(s) of such organ(s) is accountedfor by means of gating. Subsequently, another signal or process,typically corresponding mainly to a change in the location of suchorgans, is accounted for by means of an image tracker. For example, inthe case of the heart and/or associated blood vessels, gating to the ECGsignal is applied to create one or more video streams, each of which isstabilized with respect to a specific phase in the cardiac cycle. Imagetracking is then applied to the aforementioned gated video stream(s) inorder to further stabilize the stream(s) with respect to the respiratorycycle.

In some embodiments, gating followed by image tracking is applied torespective image frames, in a frame-by-frame manner, such that anindividual gated frame is image tracked prior to the next gated framebeing acquired. Alternatively, gating is applied to a batch of imageframes to generate a set of gated image frames. Image tracking is thenapplied to the set of gated image frames.

In some embodiments, the image tracker is applied to motion that istypically not of a cyclical nature, such as whole-body motion of thepatient in the course of the procedure. As a result, such motion of thepatient is absent from, or substantially reduced in, the stabilizedimage stream being viewed by the physician.

The sequence in which the aforementioned gating, image tracking and gapfilling are applied to images in the originally-acquired image streammay vary.

In some embodiments, and for the purpose of creating a stabilized videostream of a cyclically-moving organ, the typically higher frequency oftwo physiological signals or processes corresponding to a motion of saidorgan is gated, and subsequently the signal or process which istypically of a lower frequency, and/or any additional motion of theorgan, is accounted for by means of image tracking. For example, suchsequence may reduce the computational resources required for imagestabilization. Alternatively, the typically lower frequency of the twophysiological signals or processes is gated, and the signal or processwhich is typically of a higher frequency, and/or any additional motionof the organ, is accounted for by means of image tracking.

In some embodiments, the stabilization of the video stream of thecyclically-moving organ is achieved by accounting for the secondaforementioned signal or process by means of image tracking prior to(and not following) accounting for the first aforementioned signal orprocess by means of gating. For example, such a sequence may be usefulin some of the aforementioned gap-filling algorithms. Specifically, forsome applications, visual information of changes in tool positionsrelative to anatomical landmarks is easier to identify in image trackedimages before the images are gated.

In some embodiments, image tracking followed by gating is applied torespective image frames (typically, in real time or near real time).Alternatively, a batch of image frames are image tracked andsubsequently the tracked image frames are gated.

In some embodiments, image frames are gated with respect to therespiratory cycle, and are image-tracked with respect to movementrelated to the subject's cardiac cycle.

The image tracker applied in the aforementioned embodiments may be anedge tracker, a centroid tracker, a correlation tracker, an objecttracker, or any combination thereof. Such image tracker typicallyneutralizes, in the eyes of the viewer of a stabilized video stream, thechange in location of the organs being imaged, thus maintaining theorgan at a desired location on the display (such as its center), eventhough the organ being imaged is in constant motion.

Reference is now made to FIG. 3 which is a schematic illustration of avideo stream 33 of a subject's heart being gated to a phase of thesubject's cardiac cycle, in accordance with an embodiment of the presentinvention. A video camera 31, acquires a video stream 33 of thesubject's heart. An ECG 32 detects the subject's cardiac cycle. A gatingprocessor 34 of control unit 13 (FIG. 1) selects image frames 35corresponding to a given phase of the cardiac cycle as reflected by agiven point in ECG 32. In some embodiments, a buffer 36 is used for gapfilling the transitions among images 35. The resulting stabilized videostream is presented on display 37. Reference is now made to FIG. 4,which is a schematic illustration of a video stream 41 of a subject'sheart being image tracked, in accordance with an embodiment of thepresent invention. Typically, video stream 41 is the output of gatingprocessor 34 (FIG. 3). A mask 45 is generated from image frames of videostream 41 of the subject's heart. Both mask 45 and the image frames arefed into a correlator 42. Correlator 42 identifies mask 45 in each newimage frame, and by doing so identifies the deviation in the location ofthe mask within the current image frame relative to its location in theprior image frame. Image corrector 43 utilizes the output of correlator42 for realigning each new image frame such that the relative locationof mask 45 within each such new image frame remains constant.Consequently, tracked video stream 44 is produced. In embodiments inwhich the input to correlator 42 and image corrector 43 is the output ofgating processor 34 (FIG. 3), video stream 44 is both image tracked andgated to a given point in the ECG.

Reference is now made to FIG. 5, which is a schematic illustration of avideo stream of a subject's heart being (a) gated 51 to a phase of aphysiological cycle (as described with reference to FIG. 3), and (b)image tracked 52 (as described with reference to FIG. 4), in accordancewith an embodiment of the present invention. The combined application ofprocesses 51 and 52 typically results in a video stream that isstabilized with respect to changes in the shape as well as the locationof the organ(s) being imaged.

Typically, when using the combined application of gating and imagetracking as in the sequence shown in FIG. 5, the aforementionedsmoothening or gap filling in the transformations among selected imageframes is performed on the output of the gating and the image tracking(i.e., on the output of FIG. 5). In such a case, each individual imageframe which is an output of the gating serves as an input for imagetracking. After going through both gating and image tracking, eachindividual frame becomes both gated and image tracked, and the gapfilling is performed on the transformations between successivegated-and-image-tracked frames.

It is noted that, as described, the scope of the present invention alsoincludes performing image tracking prior to performing gating(configuration not shown in the figures). In this case, the smootheningalgorithms described herein are generally applied to the output of thegating.

In some embodiments, a path for passing tools into desired locations inthe heart and/or coronary blood vessels is generated. In someembodiments, such a path is also displayed.

In some embodiments, stabilized road mapping is applied tocyclically-moving organs such as the coronary blood vessels, thepulmonary vessels, the aorta, and/or to the heart itself. Road mappingis typically helpful in reducing radiation time and/or the amount ofcontrast agent being used to facilitate medical procedures. Road mappingis commonly used in catheterization procedures in organs that cantypically remain motionless throughout the procedure, such as bloodvessels in the limbs. One embodiment of road mapping is named DigitalSubtraction Angiography (DSA).

The use of road mapping is typically difficult with conventional,constantly moving cardiac images, because the historical roadmap and thedisplayed images are typically not aligned with one another most of thetime. Thus, road mapping is typically not used in procedures performedon moving organs, such as coronary interventions.

In some embodiments of the current invention, a historical roadmap whichwas generated in the same phase of the cardiac cycle to which thedisplayed, stabilized video stream is gated and from the same viewingangle, is displayed as a background to the real-time, stabilized videostream. (In some embodiments, the aforementioned use of image trackingis also applied, for example, in order to compensate for the effect ofthe respiratory cycle.) The roadmapping typically generates an image ofthe coronary vessels highlighted with a contrast agent. Consequently,the real-time image of tools inserted through such vessels is typicallyviewed as superimposed on the roadmap of those same vessels at the samegated phase in the cardiac cycle. In some embodiments, by generating astabilized roadmap, manipulation of tools is facilitated, and/orcumulative radiation throughout the procedure is reduced, and/or thecumulative amount of contrast agent injected throughout the procedure issmaller.

Typically the contrast agent is injected into a space within thesubject's cardiovascular system, for example, a chamber of the subject'sheart, a coronary blood vessel, and/or the subject's aorta.

In some embodiments, using roadmapping facilitates the direct stentingof the subject's coronary arteries, without requiring a prior step ofpre-dilatation. In such embodiments, the roadmap typically improves theability to place the stent accurately and thus reduces the need toinflate a balloon which does not carry a stent prior to the deploymentof the stent itself. That, in turn, typically reduces procedure timeand/or cost.

In some embodiments, direct stenting as described herein is capable ofreducing the risk of embolization which may otherwise be created ifpre-dilatation is performed at a slightly different location from thatof the subsequent deployment of the stent. If such a difference inlocation exists, then the occluding substance or tissue that is beinginflated and fragmented by a pre-dilatation balloon may not besubsequently kept in place by the stent, and thus embolization mightoccur.

Generation of the aforementioned roadmap is typically benefited byknowledge by the system of when contrast agent is being injected. Insome embodiments, the injection of contrast agent for highlighting thevessels is sensed, for the purpose of generating the aforementionedroadmap, via an electrical signal indicating the activation of theinjection sub-system. Alternatively or additionally, the injection ofcontrast agent for highlighting the vessels is identified by means ofimage processing. Further alternatively or additionally, the injectionof contrast agent for highlighting the vessels is identified by means ofanalyzing changes in the image (such as via a histogram) of the regionat the distal end of the catheter from which the contrast agenttypically comes out (such as a guiding catheter in the case of coronaryroad mapping). Changes in the image include a relatively abrupt changein the color and/or grayscale level (darkness) of a relatively largenumber and/or portion of image pixels, or the appearance of vessel-likefeatures in the image, etc., or any combination thereof. It is notedthat by assessing a change in the darkness level to identify the time ofinjection of the contrast agent, the control unit may identify a darkerarea of the image or a lighter area of the image, depending on whetherthe contrast agent is represented as dark or light. It is additionallynoted that whereas specifically assessing the region at the distal endof the catheter typically enhances signal to noise (because this regionis most likely to show an abrupt change), the scope of the presentinvention includes assessing all of the acquired image data to identifythe injection of the contrast agent.

In some embodiments, the road map being displayed in conjunction withthe stabilized video stream loops among multiple images of differentmoments in the injection and dissipation process of the contrast agent,wherein all of those images were originally gated to a same phase in thecardiac cycle to which the currently-displayed, stabilized video streamis gated.

In some embodiments, the road map being displayed in conjunction withthe stabilized video stream comprises an image of the contrast agentitself. In some embodiments, the road map comprises a synthesizedbackground(s), enhancement(s), contour(s), pattern(s), texture(s),shade(s) and/or color(s) that was created based upon the visualinformation acquired from the injection and/or dissipation of contrastagent, using computer graphics and/or image processing techniques. Insome embodiments, the gray level of the road map is inversed, such thatthe road map appears light against a darkened background.

In some embodiments, the summation or combination of two road mapsgenerated at different times in the procedure is displayed. In someembodiments, a road map generated during a given phase of a firstcardiac cycle is summed with a road map generated during a same phase ofa second (typically immediately subsequent) cardiac cycle, to create acombined road map that displays more coronary vessels and/or displayscoronary vessels with greater clarity. In some embodiments, in the caseof a total or partial occlusion in a coronary vessel, the combined roadmap may comprise the summation or combination of a roadmap created froman injection of a contrast agent proximally to the occlusion, and asecond road map created from an injection of a contrast agent distallyto the occlusion, such as via a collateral vessel and/or in a retrogradedirection. In these embodiments, the roadmaps based on the proximally-and distally-injected contrast agent are created in the same phase ofone or more cardiac cycles that are not necessarily adjacent cardiaccycles.

In some embodiments, a three-dimensional road map is constructed bycombining two or more two-dimensional road maps recorded from viewingangles that are typically different by 30 degrees or more. In someembodiments, the two two-dimensional road maps (from which athree-dimensional road map is constructed) are recorded concurrentlyfrom two different viewing angles by means of a bi-plane fluoroscopysystem. In some embodiments, a three-dimensional road map is createdfrom CT angiography images, typically pre-procedural ones, and thencorrelated with the real-time two-dimensional road map created fromintra-procedural angiography. In some embodiments, a three-dimensionalroad map is constructed from two or more different images taken from thesame viewing angle but during different phases in the cardiac cycle.

In some embodiments, markings are applied upon the stabilized images.For example, in the case of coronary angioplasty, such markings may beapplied to the longitudinal edges of an occlusion, or to the region inwhich pre-dilatation was performed, etc. In some embodiments, suchmarkings are applied manually with an input device such as a computermouse, or by a stylet in the case of a tablet computer. In someembodiments, such markings are applied by hand on a touch screen. Insome embodiments, such markings appear to the viewer, throughoutsubsequent changes in the viewing angle and/or zoom level or thefluoroscopy/angiography system, as if they remain attached to the bloodvessels to which they refer. Such virtual attachment is typicallyperformed by means of image processing. In some embodiments, themarkings comprise a scale or a grid that is generated on the stabilizedimage, to indicate to the physician the dimensions of the image.

In some embodiments, on-line geometric and/or hemodynamic measurements(e.g., size, flow, ejection fraction) are made and/or displayed upon thestabilized images. “On-line” in this context means that the measurementsare made on the stabilized image stream, as opposed to being made onfrozen images extracted from an image stream. For example, in the caseof angioplasty, such measurements, also known as Quantitative CoronaryAnalysis (QCA), may include the length and inner diameter(s) of theocclusion and be used as inputs for the selection of a balloon and/or astent. In some embodiments, the known size of an object seen in thestabilized images, such as the outer diameter of an introducing catheteror the size of a patch adhered to the patient's chest or the distancebetween radiopaque markers on a tool, is used as a reference in makingsuch measurements. In some embodiments, the orientation at which themedical tool is disposed within the subject's body is determined, bydetermining an apparent distance between radiopaque markers on a toolwithin the stabilized set of image frames, with respect to the knowndistance of the markers from each other. In some embodiments, thephysical size corresponding to an image pixel, as known from the imagingsystem, is used as a reference (in which case no physical referenceobject is required).

In some embodiments, the deployment of an endovascular device, forexample a balloon or a stent, is visually simulated prior to actuallybeing performed. For example, a virtual stent of selected length anddiameter may be visually placed and displayed, within the stabilizedimage stream, as if it were situated at the site of the occlusion. Thesuitability of the intended dimensions as observed with the virtualstent can then be visually validated by the physician prior to selectingand deploying the physical stent. For some applications, multiplevirtual stents, such as in preparation for the stenting of a vascularbifurcation where a physical stent will be required in each branch, arevirtually placed and matched with one another prior to their actualdeployment. In some embodiments, a virtual stent is placed in proximityto a physical, already-deployed stent to verify that the two match oneanother prior to deploying the second, physical stent.

In some embodiments, the proper deployment of a virtual tool isestimated by viewing it upon two stabilized images streams, eachcorresponding to a different phase of the cardiac cycle. In someembodiments, one such phase is diastolic while the second phase issystolic. In some embodiments, in response to determining an orientationat which a real medical tool (e.g., a catheter) is disposed within thesubject's body, the virtual tool is deployed at a corresponding (e.g.,identical) orientation.

In some embodiments, an operator manipulates an image of a virtual tooldeployed within the stabilized image stream, until the virtual tool isof appropriate dimensions. A reference number of a real tool that bestcorresponds to the dimensions of the virtual stent is generated. (Thereference number may be, for example, a catalog number of a real tool.)Alternatively or additionally, the dimensions of a real tool thatcorresponds to the dimensions of the virtual tool are generated. In someembodiments, image processing is applied to the simulated image of thevirtual stent to determine the curvature of a region in which thevirtual stent is deployed and dimensions of a real tool are generatedthat incorporate the curvature of the region. In some embodiments, theorientation of the region in which the virtual tool is deployed isdetermined in order to generate the dimensions of a corresponding realtool.

In some embodiments, the proper deployment of an actual stent isassessed by viewing the stent within two stabilized images streams, eachcorresponding to a different phase of the cardiac cycle. In someembodiments, one such phase is diastolic, while the second phase issystolic.

In some embodiments, image processing techniques are applied to enhancethe image of (a) an endovascular device, and/or (b) radiopaque markerswhich a device comprises, and/or (c) the walls of the vessel in whichthe device is situated, within the stabilized image stream. For example,the device may be a balloon and/or a stent that is implanted in thesubject's body or that is transiently placed within the subject's body.Typically, such enhancement is more easily generated in a stabilizedvideo stream in which the enhanced object is relatively stable, comparedwith in a non-stabilized stream of images wherein the object beingenhanced is constantly shifting. In accordance with embodiments of theinvention, such enhancement may be performed on-line, within thestabilized image stream. Consequently, in such embodiments, properdeployment of the endovascular device being deployed may be verified bythe physician during a procedure.

In some embodiments, the stabilized image stream is used for on-linemeasurement of the flow within a vessel, by measuring the time it takescontrast agent to travel a known distance. In some embodiments, thestabilized image stream is used for on-line measurement of thesaturation of contrast agent within targeted tissue, such as heartmuscle.

In some embodiments, additional images, such as images produced by othermodalities in a same or similar phase of the cardiac cycle to which thestabilized video stream is gated, are co-displayed. For someapplications, such images are pre-operative, intra-operative, or acombination of the two. Alternatively or additionally, such images aretwo-dimensional or three-dimensional. The modalities from which suchimages originate are used before or during coronary procedures andinclude, without limitation, fluoroscopy, CT, MRI, CT angiography, TransEsophageal Echo (also known as TEE), Trans Thoracic Echo (also known asTTE), Intra Vascular Ultrasound (also known as IVUS), Intra CardiacUltrasound (also known as Intra Cardiac Echo, or ICE), Optical CoherenceTomography, Intra Vascular MRI, or any combination thereof. In someembodiments, the co-display of such images together with theaforementioned gated video stream is performed via fusion (e.g., imageoverlay), using image-to-image registration techniques. Such aco-display typically provides the operator with enhanced clinicalinformation.

(Throughout the specification and the claims, the term “overlay” andderivations thereof, should not be understood to denote a particularorder in which two or more images are combined. Rather, it refersgenerally to the combination of two or more images that are overlaid inspace.)

In some embodiments, a first set of images are acquired by a firstimaging device from outside a portion of the subject's body, for exampleby CT or using a fluoroscope. A second set of images are acquired by asecond imaging device from within the portion of the subject's body, forexample, using an intra-vascular ultrasound probe, or an intra-vascularMRI probe. In some embodiments, the first set of images are acquiredbefore the second set of images are acquired, and the two sets of imagesare registered to each other. Alternatively, the first imaging deviceand the second imaging device acquire the respective sets of imageframes simultaneously.

In some embodiments, images generated by an ultrasound probe (such asIVUS) within a coronary vessel are used in conjunction with thestabilized image stream (such as a stabilized fluoroscopic image stream)in the following manner:

i. The fluoroscopic image stream is stabilized.

ii. An IVUS catheter is inserted to the site of an occlusion underfluoroscopic imaging, to inspect endoluminal anatomy.

iii. The image slices generated by the IVUS are recorded and stored intandem with the visual location (such as display coordinates) of thedistal tip of the IVUS catheter as seen by the fluoroscopy.

iv. The IVUS catheter is retrieved to make room for balloon/stentdeployment.

v. A catheter with a balloon and/or stent is inserted to the site of theocclusion, under fluoroscopic imaging.

vi. The location of the distal tip of the catheter carrying the balloonand/or stent is visually recognized (such as via display coordinates).

vii. The IVUS images previously recorded at the same location aredisplayed, together with the fluoroscopic images. In some embodiments,the IVUS images are displayed in a separate window (but on the samescreen as the fluoroscopic images). In some embodiments, the IVUS imagesare displayed on a separate screen. In some embodiments, the IVUS imagesbeing displayed are two-dimensional (also known as “slices”). In someembodiments, a three-dimensional “tunnel-like” reconstruction of theIVUS images of the vessel (or a section thereof) is displayed. In someembodiments, the IVUS images are overlaid on the fluoroscopic images. Insome embodiments, the IVUS images are fused with the fluoroscopicimages.

viii. As a result, the balloon and/or stent may be deployed based uponan on-line combination of real-time fluoroscopic images and of IVUSimages recorded earlier (for example, several minutes earlier).

Although embodiments of the invention are, described primarily withreference to the heart, connecting vessels (e.g., aortic, pulmonary) andcoronary blood vessels, embodiments of the current invention aresimilarly applicable to any other organ affected by periodic motionand/or periodic activity. An example for the latter would be the brain.

Reference is now made to FIG. 6, which is a schematic illustration ofapparatus for synchronizing actuation of a medical device with aphysiological cycle, in accordance with an embodiment of the presentinvention. Cyclically-moving organ 61 is imaged by imaging device 62.Non-gated image frames are displayed on display 64. A cyclicalphysiological signal used for synchronization is transmitted via line 68to processor 63. Gated image frames are displayed on display 66, whichis connected to processor 63. In some embodiments, gap filling isapplied to the gated image frames. In some embodiments, such images arealso image tracked. Actuator 65 is actuated in a synchronized manner,with respect to the synchronization signal transferred from processor 63via a line 69. Actuator 65, in turn, controls tool 67, which is appliedto organ 61.

The scope of the present invention includes synchronizing, with respectto a physiological cycle, the actuation and/or movement of a medicaldevice that performs a function on a portion of a subject's body,without stabilizing images of the portion,

The scope of the present invention includes synchronizing, with respectto a physiological cycle, the actuation and/or movement of a medicaldevice that performs a function on a portion of a subject's body, incombination with stabilizing images of the portion.

The scope of the present invention includes synchronizing, with respectto a given phase of a physiological cycle, the actuation and/or movementof a medical device that performs a function on a portion of a subject'sbody, and stabilizing images of the portion with respect to the samegiven phase of the cycle.

FIGS. 7A-C and 8 through 12 are schematic illustrations of apparatus forinflation of a balloon, such as for widening an occlusion within acoronary blood vessel, in synchronization with the patient's cardiaccycle, in accordance with respective embodiments of the invention. Insome embodiments, a stent, which is positioned around the balloon, isexpanded by inflating the balloon. In some embodiments, the embodimentsshown in FIGS. 7-12 are practiced in combination with stabilized imagingtechniques described hereinabove.

Typically, the placement and inflation of the balloon is performed in asame selected specific phase of the cardiac cycle. That typically leadsto accuracy in the placement of the balloon at a given location.

In cases where a single cardiac cycle is shorter than the time it takesto easily or safely inflate a coronary balloon, inflation in someembodiments is performed in an intermittent (i.e., a stepwise) manner,in the course of a same selected phase in multiple cardiac cycles (FIG.7C).

In other embodiments, one or more segments of the inflation of theballoon is performed continuously (i.e., not in synchronization to thecardiac cycle) and one or more segments of the inflation of the balloonis performed in the aforementioned synchronized, stepwise manner. In oneembodiment, synchronized inflation until the balloon becomes fixed tothe inner wall of the lumen is followed by continuous inflation untilthe balloon is inflated to a target diameter or volume. In anotherembodiment, the balloon is inflated continuously till it reaches a givenvolume but is not yet fixed to the inner walls of the lumen, followed bysynchronized inflation until it becomes fixed to the inner walls of thelumen. In a third embodiment, the balloon is first inflated continuouslyuntil it reaches a given volume, then inflated in a synchronized manneruntil it becomes attached to the inner wall of the lumen, and theninflated continuously again until it reaches a desired diameter orvolume.

In some embodiments, the aforementioned synchronized placement andinflation are performed while viewing the aforementioned stabilizedimage as described with reference to FIG. 1.

In some embodiments, the specific phase to which the inflation of theballoon is synchronized is the end of the diastole phase of the cardiaccycle. At the end-diastolic phase of the cardiac cycle, the ventriclesare typically at their fullest volume. Furthermore, the inventorshypothesize that during the end-diastolic phase of the cardiac cycle,the coronary arteries are typically the most spread apart, and typicallyremain in that situation for a fraction of a second. Such timing mayfurther assist in the correct apposition of a stent positioned upon theballoon. Alternatively or additionally, the inflation of the balloon isgated to a different phase of the subject's cardiac cycle, for example,a mid-diastolic phase or a systolic phase.

Reference is now made to FIGS. 7A-B, which are schematic illustrationsof the actuation of inflation of a balloon 73 in synchronization with aphysiological cycle, in accordance with an embodiment of the presentinvention. As shown in FIG. 7A, blood vessel 71 is clogged by occludingsubstance or tissue 72. Balloon 73 is positioned at the occlusion andinflated by actuator 75 via a tube. According to some embodiments of thecurrent invention, a synchronization signal derived from the patient'sECG is provided via line 74. The ECG signal is used to trigger theincreased inflation pressure of balloon 73 in a stepwise manner, whereineach step occurs in the same selected phase of the ECG cycle. The resultis sequence 76 (FIG. 7B), showing the steady, synchronized stepwiseinflation of the balloon, until the balloon is typically inflated to thedesired extent and at is the desired location.

In some embodiments, actuator 75 is connected to a typicallynon-synchronized inflation device. In another embodiment, actuator 75and the inflation device are integrated together into a single,synchronized inflation device.

Reference is now made to FIG. 7C, which is a graph showing the pressure77 of the balloon as a function of time, in accordance with anembodiment of the present invention.

Reference is now made to FIG. 8, which is a schematic illustration ofapparatus for facilitating the synchronized inflation of a balloon 82,in accordance with an embodiment of the present invention. The operatorof the device actuates a handle 81 (such as via rotating), in order toinflate balloon 82. Handle 81, by means of control circuit 83, commandsdriver 84. Driver 84 is synchronized by a train of pulses 85 (whichoriginates from the ECG as explained previously), such that it producesa synchronous output into a torque motor. The torque motor comprises astator 86 and rotor 87. The torque motor rotates a lead screw 88.Stationary drive nut 89 converts the rotational motion of lead screw 88into the linear motion of piston 810. The motion of piston 810 insidecylinder 811 pushes the fluid contained within the distal portion ofcylinder 811 into inflation tube 812, and from there into balloon 82.

FIGS. 9-11 are schematic illustrations of apparatus for facilitating thesynchronized inflation of a balloon, in accordance with anotherembodiment of the present invention. Inflation device 91 and ballooncatheter 92 are typically the same as those conventionally used fornon-synchronized balloon inflation. In some embodiments, synchronizationof balloon inflation to the patient's cardiac cycle is enabled by anaccumulator-modulator 93 that is added and is typically connectedbetween inflation device 91 and balloon catheter 92. The output ofinflation device 91, typically in the form of inflation fluid, feedsaccumulator-modulator 93. The output of accumulator-modulator 93,typically in the form of inflation fluid, feeds balloon catheter 92.

The purpose of accumulator-modulator 93 is to enable intermittentballoon inflation that is performed, in whole or in part, in a stepwisemanner and in synchronization with the patient's ECG signal. Themodulator part of 93 is typically responsible primarily for thesynchronization of the inflation to the ECG. The accumulator part of 93is typically responsible primarily for maintaining a continuous build-upof the inflation pressure despite the inflation itself being (in wholeor in part) intermittent. (Without the accumulator, undesirableincreases and decreases in the inflation pressure may occur.)

FIG. 10 is a schematic illustration of an embodiment ofaccumulator-modulator 93 described with respect to FIG. 9. Theaccumulator unit comprises a loaded piston 101. The modulator unitcomprises valve 102, driver circuit 103 and internal power supply 104.Internal power supply 104 is optional, as an alternative to an externalpower supply. Driver circuit 103 is fed by the ECG-derivedsynchronization signal via line 107, and based on that signal drivesvalve 102 to assume the open and closed positions. In an embodiment, theaccumulator-modulator receives its input, typically in the form ofinflation fluid, from an inflation device via inlet 105. Theaccumulator-modulator typically provides its output, typically in theform of inflation fluid, to a balloon catheter via outlet 106.

As noted above, the modulator unit of the accumulator-modulatordescribed with respect to FIG. 9 and FIG. 10 typically comprises a valvethat opens and shuts in accordance with the ECG-derived synchronizationsignal and through which the inflation fluid traverses. Such a valve maycomprise any known implementation, including a check valve of any type(e.g., ball check, duckbill, swing check, clapper, stop check), a leafvalve, or any combination thereof.

FIG. 11 is a detailed schematic illustration of theaccumulator-modulator described with respect to FIG. 9 and FIG. 10, inaccordance with an embodiment of the present invention. Inflation fluidtraverses flexible tube 111 on its way towards the outlet of theaccumulator-modulator. Tube 111 changes intermittently between beingopen and shut for the flow of such fluid. Two arms 112, pivoting on axes115, intermittently squeeze and release tube 111. The activation of coil113 causes arms 112 to pull closer to one another for minimizing themagnetic field reluctance, and thus squeeze tube 111 shut. When coil 113is deactivated, arms 112 (with the assistance of an optional recoilspring 114) pull apart and cause tube 111 to open for the passage ofinflation fluid.

Reference is now made to FIG. 12, which is a schematic illustration ofapparatus for facilitating the synchronized inflation of a balloon, theapparatus being built into an inflation device, in accordance with afurther embodiment of the present invention. A pressure signal 125 iscreated by inflation mechanism 126. An ECG-derived synchronizationsignal 121 and pressure signal 125 are both fed into controller 122. Asynchronized actuation signal 123 is fed from controller 122 to valvemodulator 124. The output of valve modulator 124, typically in the formof inflation fluid, is fed into a balloon catheter that is typicallyconnected distally to the inflation device. As a result, the balloon isinflated gradually, in a stepwise manner, to a desired size.

Each of the aforementioned balloon inflation apparatuses and methods,described with respect to FIGS. 7 through 12, may be synchronized eitherto the patient's ECG signal, blood pressure signal, displacement signal,vibration signal or to a different signal corresponding to the patient'scardiac cycle, or to any combination, derivation, extrapolation ormanipulation thereof.

In some embodiments, the aforementioned balloon inflation apparatusesand methods described with respect to FIGS. 7 through 12 apply not onlyto the placement and inflation of a balloon, but also to the deploymentof a stent which is positioned upon the balloon. Typically, deploying astent in a virtually stable environment leads to greater accuracy in theplacement of the stent at a given location. In some embodiments, othermedical tools which are positioned upon the balloon are deployed via theinflation of the balloon. For example, a valve, a graft, aseptal-closure device, and/or another medical tool may be deployed viathe inflation of the balloon.

In some embodiments, while causing the inflation of the balloon to occur(in whole or in part) in a stepwise manner in synchronization with theECG signal, the aforementioned balloon inflation apparatus and methodsdescribed with respect to FIGS. 7 through 12 provide the operator of theinflation device with continuous force feedback during inflation. Thus,the operator of the inflation device typically feels as if the ballooninflation process is continuous even though that process, or partsthereof, is in fact intermittent. In some embodiments, the apparatussmoothens the force feedback with respect to the physiological cycle towhich the inflation is gated, so that the effect of the stepwiseinflation, on the force feedback to the operator, is reduced.

Although embodiments of synchronizing the actuation, and/or the movementof a tool to a physiological cycle, have been described with respect toa balloon, the scope of the invention includes applying theseembodiments to the other medical tools described herein.

FIGS. 13 through 15 disclose embodiments of the synchronized applicationof a guide wire, such as for opening an occlusion in a coronary bloodvessel, in accordance with an embodiment of the present invention. Insome embodiments, application of the guide wire is synchronized eitherto the patient's ECG signal, or to a different signal corresponding tothe patient's cardiac cycle, or to any combination, derivation,extrapolation or manipulation thereof.

Reference is now made to FIG. 13, which is a schematic illustration ofsynchronization of the penetration of an occlusion 132 of a blood vessel131 with cyclic movement of the blood vessel, in accordance with anembodiment of the present invention. In the case of a total ornear-total occlusion, such penetration typically precedes the inflationof a balloon and/or the placement of a stent. Wire 133 penetrates theocclusion in a synchronized, stepwise manner. An actuator 135,synchronized by signal 134 coming from the patient's ECG, is used togenerate the stepwise forward motion as seen in schematic sequence 136.Typically, such synchronized forward motion of the wire 133 enablesthese embodiments of the current invention to reduce the probability ofperforation or dissection of blood vessel 131 by the guide wire.Conversely, in conventional procedures, such perforation or dissectionis known to occur, typically due to pushing the wire at a phase in thecardiac cycle where the wire actually points at the wall of the vesseland not towards the desired point of entry on the surface of theocclusion.

In some embodiments, synchronization is made to a phase in the cardiaccycle when the coronary arteries are typically maximally inflated andthus with the largest cross section. Such timing may assist in openingthe occlusion.

In some embodiments, the operator feels as if he or she pushes the wirecontinuously, while the actuator causes the wire to be pushedintermittently, in synchronization with the ECG signal.

In some embodiments, the aforementioned synchronization is applied to atool used for widening or opening occlusions, where the tool is not aguide wire. In some embodiments, synchronization is applied to thetool's motion within the occlusion. In some embodiments, anocclusion-opening tool, for example a tool having jackhammer-likefunctionality, is moved toward the occlusion during the given phase ofrespective cycles. Typically, after the tool is moved toward theocclusion at the given phase of a first cycle and before the tool ismoved toward the occlusion at the given phase of a subsequent cycle thetool is retracted from the occlusion. In another embodiment,synchronization is used to control the release of energy, for example,ultrasonic energy, aimed at widening or opening the occlusion.

Reference is now made to FIG. 14, which is a schematic illustration of amodulator for synchronizing the penetration of an occlusion of a bloodvessel by a wire 141 with the cyclic movement of the blood vessel, inaccordance with an embodiment of the present invention. The modulatorgenerates stepwise motion of wire 141. The modulator disclosed herein isan embodiment based on a self-locking clamp 143 driven by a voice coilincorporating a coil plunger 145 and a permanent magnet stator 146. Areturn spring 142 is also incorporated. Other modulators capable ofgenerating periodic motion that are known in the art include, but arenot limited to, those based on roller wheels, grippers, or piezoelectricor magnetostrictive effects. The modulator is typically housed in shellor housing 144. Wire 141 can be placed into the modulator at any desiredposition along the wire, for example after the interventionalcardiologist has already pushed the wire all the way to the occlusion.

In some embodiments, similar modulating heads yield rotational motion ofthe wire by adding a torque generator to the modulator.

Reference is now made to FIG. 15, which is a schematic illustration of ahandheld actuator that comprises the modulator described with respect toFIG. 14, in accordance with an embodiment of the present invention.Electronic circuit 152 conveys a driving signal to modulator 153, in themanner already described with respect to FIG. 14. Control stick 151controls the motion of guide wire 155. For example, when the operatorpushes stick 151 forward, or activates a trigger, the actuator conveys acorresponding train of pulses to modulator 153. These pulses aresynchronized via line 154 to the reference signal. The pulse train, whendelivered to the modulator, creates the forward motion of the guide wirein a synchronized stepwise manner. Typically, the harder operator pushescontrol stick 151, the more intense are the pulses, hence wire 155 willmove forward at a higher pace. By pulling stick 151 backwards, the guidewire will move correspondingly backwards. In some embodiments, the forcefeedback provided to control stick 151 is spring loaded. In someembodiments, a force feedback that bears greater resemblance to theoriginal force feedback of wire 155 is generated. For example, forcefeedback that does not vary with respect to the cyclic activity of theblood vessel, or force feedback that is smoothened with respect to themovement of the blood vessel, may be generated.

In some embodiments, the operator exerts force on guide wire 155directly, and not indirectly via control stick 151 as is describedabove.

In some embodiments, the actuator provides custom force feedback whichtypically increases its user-friendliness by providing the operator witha more familiar feel. In some embodiments, the actuator (andspecifically the control stick) replicates the tactile feedback ofspecific medical tools, thus increasing its utility to the operator. Insome embodiments, a digital library of tool-specific force feedbacks isconnected to the actuator. In some embodiments, the force feedbackspecific to each tool is selected by the operator. In some embodiments,the force feedback specific to each tool is selected automatically, withthe actuator identifying the tool (such as via a specific code).

In some embodiments, the aforementioned actuator controls theapplication of:

-   -   linear motion,    -   angular motion (e.g., for the purpose of turning the tip of the        penetrating device and, for example, for leading a drill through        an occlusion in a coronary blood vessel synchronized with the        cardiac cycle),    -   energy (e.g., for radio frequency ablation synchronized with the        cardiac cycle, or for percutaneous myocardial revascularization        via the application of laser in synchronization with the cardiac        cycle),    -   substance delivery (e.g., gene therapy for cardiac        revascularization synchronized with the cardiac cycle), or    -   pressure, such as for inflating a balloon and/or a stent    -   any combination thereof.

In some embodiments, the aforementioned actuator comprises re-usableelements, restricted-reuse elements, single-use elements, or anycombination thereof. In some embodiments, the actuator, or elementsthereof, are usable only for a specific time period and/or a specificnumber of uses following their initial activation. In some embodiments,the time period and/or number of uses are coded in a memory element(such as a memory chip) incorporated into the actuator.

Reference is now made to FIG. 16, which is a schematic illustration ofthe stepwise transluminal placement of a coronary bypass graft 163 in acoronary blood vessel 161 in order to bypass an occlusion 162, inaccordance with an embodiment of the present invention. In the priorart, such an implantation is typically performed during open heartsurgery. In such surgery, a bypass is implanted between the proximal anddistal sides of a major impairment (such as a total occlusion) in ablood vessel. Embodiments of the current invention, by providing a fullor partial virtual stabilization as previously explained, make itpossible to connect the proximal and distal sides of impairment 162without open surgery. Based on a combination of the stabilized image ofblood vessel 161 and the synchronous activation (based upon signal 164and by means of actuator 165) of the tool(s) delivering and placing thegraft, the two sides of the impairment are connected transluminally.Typically, images generated from two separate views, sequentially orconcurrently (such as those provided concurrently by a bi-planefluoroscopy system), are used. Such views typically differ from oneanother by at least 30 degrees, and in some embodiments they areperpendicular. In some embodiments, the graft is a biological graft.Alternatively, the graft is a synthetic graft.

In some embodiments, the aforementioned modulator, modulator-accumulatorand/or actuator are not hand held. In some embodiments, theaforementioned modulator, modulator-accumulator or actuator areconnected to or operated by a medical robot. In some embodiments, theaforementioned modulator, modulator-accumulator and/or actuator areoperated in a remote manner via a communications network (e.g.,tele-operation).

For some applications, the aforementioned techniques are applied to anorgan that does not move cyclically, but is cyclically active (such asthe brain).

In some embodiments, the synchronized tools disclosed by the currentinvention are connected to, or operated by, a medical robot.

The scope of the present invention includes using the techniques ofsynchronized actuation of a tool, as described hereinabove, forapplications other than those described in detail hereinabove. Ingeneral, the techniques can be used in combination with the techniquesdescribed hereinabove, for stabilized imaging of a cyclically movingorgan. In some embodiments, movement of a tool in a given direction oralong a desired pattern is synchronized with a physiological cycle.Typically, the tool is moved in the given direction at a given phase ofrespective physiological cycles without moving the tool in the oppositedirection to the given direction, between movements of the tool in thegiven direction.

In some embodiments, a tool is moved in a given direction by moving thecenter of the tool. In some embodiments, at a given phase of respectivecycles of a physiological cycle, a tool is actuated either to perform afunction, or to move. For some applications, at a given phase of asingle cycle of a physiological cycle, a tool is actuated tomechanically perform a function with respect to a portion of thesubject's body that moves as a result of the cycle. For example, thetechniques described hereinabove can be applied to the followingadditional procedures:

-   -   Percutaneous placement, replacement or repair of a cardiac valve        such as an aortic valve, a mitral valve, a pulmonary valve, or a        tricuspid valve. The percutaneous approach may be transvascular        or through an incision (such as transapical). It is important to        deploy the valve accurately, relative to the surrounding        anatomy. Doing so in a beating heart or vessel is often        difficult. In accordance with some embodiments of the current        invention, a tool carrying a valve is led to, and/or positioned        at, and/or actuated to deploy the valve at a desired anatomical        location in synchronization with a selected phase of the cardiac        cycle. In some embodiments, the selected phase is when the        corresponding anatomy is at a peak dimension. In some        embodiments, the selected phase of the cycle is when the        corresponding anatomy remains stable, or relatively stable, for        the longest duration. In some embodiments, the tool and the        anatomy are viewed in an image stream that is stabilized at a        same selected phase of the cardiac cycle. In some embodiments,        the selected phase at which the tool is moved, positioned,        activated or applied is the same selected phase at which an        observed image stream is stabilized. In some embodiments, the        valve is deployed by expanding the valve at the selected phase        during a single cycle. Alternatively, the valve is deployed by        expanding the valve in a stepwise manner, at the selected phase,        during more than one cycle.    -   Catheterization of pulmonary arteries, applying the tools and        techniques (e.g., guide wire, balloon, stent, occlusion-opening        devices) previously described in the context of the coronary        arteries. In some embodiments, such a procedure is performed in        conjunction with stabilized imaging as described hereinabove. In        another embodiment, such a procedure is performed not in        conjunction with stabilized imaging, but yet in synchronization        with the cardiac cycle, so as to achieve improved deployment of        a balloon or a stent, or better penetration of an occlusion.    -   Closure of holes in the septal wall, such as patent Foramen        Ovale (PFO) and Atrial Septal Defect (ASD), within the        cyclically-moving heart. With embodiments of the current        invention, a carrier carrying a closure device is led to, and        positioned at, a desired anatomical location (such as the site        of the hole in the septum) while both carrier and heart anatomy        are viewed in an image stream that is typically stabilized at a        selected same phase in the cardiac cycle. Next, the closure        device is deployed (including its assembly, expansion and/or        release from the carrier) at the desired anatomical location in        a selected phase of the cardiac cycle. Such a selected phase is        typically the same as the phase selected for the stabilization        of the image stream. In some embodiments, the closure device is        deployed by expanding the closure device at the selected phase        during a single cycle. Alternatively, the closure device is        deployed by expanding the closure device in a stepwise manner,        at the selected phase, during more than one cycle.    -   Placement of a stent graft within the cyclically-moving aorta to        treat abdominal aortic aneurysms. In accordance with embodiments        of the current invention, a carrier carrying a stent graft is        led to, and positioned at, a desired anatomical location (such        as the site of the aneurysm) while both carrier and aortic        anatomy are viewed in an image stream that is typically        stabilized at a selected same phase in the cardiac cycle. Next,        the stent graft is deployed (including its assembly, expansion        and/or release from the carrier) at the desired anatomical        location in a selected phase of the cardiac cycle. Such selected        phase is typically the same as the phase selected for the        stabilization of the image stream. In other embodiments of the        current invention, the graft is deployed at the desired        anatomical location in a selected phase of the cardiac cycle        (such as when the corresponding section of the target vessel is        at its peak dimensions), without observing stabilized imaging.        In some embodiments, the stent is a self-expansible stent.    -   Localized energy application to a tissue, such as within the        heart (e.g., cardiac ablation performed by means of radio        frequency ablation, cryoablation, laser, electrocautery, or        ultrasound to address cardiac arrhythmia). In some embodiments,        the current invention facilitates the ablation of endocardial        tissue in a desired pattern, such as a continuous line or a        series of lines, for example, to apply a Maze procedure to the        tissue. In some embodiments, movement of the ablation tool is        performed in synchronization with a selected phase in the        cardiac cycle. In some embodiments, delivery of energy is        performed in synchronization with a selected phase in the        cardiac cycle. In some embodiments, the endocardial tissue is        observed via an image stream stabilized at a selected phase in        the cardiac cycle, and movement and/or activation of an ablation        (or other) tool is applied at the same selected phase in the        course of a plurality of cardiac cycles.    -   Percutaneous myocardial revascularization, such as via creating        holes in the heart muscle in a desired pattern and by means of        an energy delivery or mechanical penetration tool. In some        embodiments, movement of the tool is performed in        synchronization with a selected phase in the cardiac cycle. In        some embodiments, the tool is actuated (such as to deliver        energy or drill a hole) in synchronization with a selected phase        in the cardiac cycle. In some embodiments, the endocardial        tissue is observed via an image stream stabilized at a selected        phase in the cardiac cycle, and movement and/or activation of        the tool is applied at the same selected phase in the course of        a plurality of cardiac cycles.    -   Delivering any material or substance, such as, for example, gene        therapy or stem cells to specific locations in the heart muscle.        In some embodiments, the current invention facilitates the        injection of a substance into the heart muscle in a desired        pattern, such as a series of points spread across a surface        area. In some embodiments, movement of the tool is performed in        synchronization with a selected phase in the cardiac cycle. In        some embodiments, delivery of the substance is performed in        synchronization with a selected phase in the cardiac cycle. In        some embodiments, the endocardial tissue is observed via an        image stream stabilized at a selected phase in the cardiac        cycle, and movement of the tool and/or delivery of the substance        is applied at the same selected phase in the course of a        plurality of cardiac cycles.    -   Suturing tissue in a cyclically-moving organ, such as in a        bypass or a valve or a graft. In some embodiments, movement of        the suturing tool is performed in synchronization with a        selected phase in the cardiac cycle. In some embodiments,        suturing is performed in synchronization with a selected phase        in the cardiac cycle. In some embodiments, the endocardial        tissue is observed via an image stream stabilized at a selected        phase in the cardiac cycle, and movement of the tool and/or        suturing is applied at the same selected phase in the course of        a plurality of cardiac cycles.    -   Trans Thoracic Needle Aspiration (TTNA), such as when a        cyclically-moving lesion within the lungs needs to be biopsied        (and while avoiding mistaken penetration of life-critical        organs). With embodiments of the current invention, an        aspiration needle is led to, and positioned at, a desired        anatomical location in the thorax (such as a lung lesion) while        both the tool and thoracic anatomy are viewed in an image stream        (such as CT images) that is typically stabilized at a selected        same phase in the respiratory and/or cardiac cycle. Next,        aspiration is performed at the desired anatomical location in a        selected phase of the cardiac and/or respiratory cycle. The        selected phase is typically the same as the phase selected for        the stabilization of the image stream.    -   Trans Bronchial Needle Aspiration (TBNA) such as when a        cyclically-moving lesion within the lungs needs to be biopsied        (and while avoiding mistaken penetration of life-critical        organs).    -   Neural stimulation in the brain with its activation gated with        the EEG signal.    -   Attaching or placing a tool at a desired location, on or within        a cyclically-moving organ.    -   Moving or directing a tool to a desired location, on or within a        cyclically-moving organ.    -   Or any combination thereof.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

1. Apparatus for use with a portion of a body of a subject that moves asa result of cyclic activity of a body system of the subject, theapparatus comprising: an imaging device for acquiring a plurality ofimage frames of the portion of the subject's body; a sensor for sensinga phase of the cyclic activity; a medical tool configured to perform afunction with respect to the portion of the subject's body; a controlunit configured to: generate a stabilized set of image frames of themedical tool disposed within the portion of the subject's body, actuatethe tool to execute an action selected from the group consisting ofperforming the function and moving, in response to the sensor sensingthat the cyclic activity is at a given phase thereof, and inhibit thetool from executing the action in response to the sensor sensing thatthe cyclic activity is not at the given phase; and a display configuredto facilitate use of the tool by displaying the stabilized set of imageframes of the medical tool disposed within the portion of the subject'sbody.
 2. The apparatus according to claim 1, further comprising a userinterface, wherein the control unit is configured to receive an inputfrom a user, via the user interface, and to designate the given phase inresponse to the input.
 3. The apparatus according to claim 1, whereinthe tool comprises a valve configured to be implanted within the portionof the subject's body by being expanded within the portion, and whereinthe control unit is configured to actuate the valve by expanding thevalve.
 4. The apparatus according to claim 1, wherein the tool comprisesa septal-closure device configured to be implanted within the portion ofthe subject's body by being expanded within the portion, and wherein thecontrol unit is configured to actuate the septal-closure device byexpanding the septal closure device.
 5. The apparatus according to claim1, wherein the tool comprises a balloon configured to perform thefunction by being inflated inside a lumen of the portion of thesubject's body.
 6. The apparatus according to claim 1, wherein the toolcomprises a tubular structure configured to bypass an occlusion of ablood vessel within the portion of the subject's body.
 7. The apparatusaccording to claim 1, wherein the tool comprises a myocardialrevascularization tool configured to sequentially apply arevascularization treatment to respective treatment sites within theportion of the subject's body, wherein the control unit is configuredto: actuate the tool to perform the function by actuating the tool toapply a revascularization treatment to a treatment site, and move thetool by moving at least a portion of the revascularization tool towardsuccessive treatment sites.
 8. The apparatus according to claim 1,wherein the tool comprises an ablation tool configured to sequentiallyablate respective ablation sites within the portion of the subject'sbody, wherein the control unit is configured to: actuate the tool toperform the function by actuating the tool to ablate an ablation site,and move the tool by moving at least a portion of the ablation tooltoward successive ablation sites.
 9. The apparatus according to claim 1,wherein the tool comprises an injection tool configured to inject asubstance within the portion of the subject's body and wherein thecontrol unit is configured to: actuate the tool to perform the functionby actuating the tool to inject the substance, and move the tool bymoving at least a portion of the tool toward an injection site.
 10. Theapparatus according to claim 1, wherein the tool comprises a needleconfigured to suture tissue within the portion of the subject's body,and wherein the control unit is configured to: actuate the tool toperform the function by actuating the tool to suture the tissue, andmove the tool by moving the needle toward successive suturing sites. 11.The apparatus according to claim 1, wherein the tool comprises a needleconfigured to aspirate tissue from an aspiration site within the portionof the subject's body, and wherein the control unit is configured to:actuate the needle to perform the function by actuating the needle toaspirate the tissue, and move the needle by moving the needle toward theaspiration site.
 12. The apparatus according to claim 1, wherein thetool comprises an occlusion-opening tool configured to perform thefunction by performing an occlusion-opening action on an at leastpartial occlusion of a lumen of the portion of the subject's body. 13.The apparatus according to claim 12, wherein the tool is configured toperform the occlusion-opening action by moving toward the occlusion, andwherein after actuating the tool at the given phase of a first cycle andbefore the actuation of the tool at the given phase of a subsequentcycle, the control unit is configured to retract the tool from theocclusion.
 14. The apparatus according to claim 1, wherein the controlunit is configured to generate the stabilized set of image frames byimage tracking at least some of the plurality of image frames to reduceimaged motion of the portion of the subject's body associated with thecyclic activity.
 15. The apparatus according to claim 14, wherein thecontrol unit is configured to generate the stabilized set of imageframes by generating a set of tracked image frames corresponding toimage frames of the portion acquired during the given phase.
 16. Theapparatus according to claim 1, wherein the control unit is configuredto generate the stabilized set of image frames by generating a set ofthe image frames corresponding to image frames of the portion acquiredduring the given phase.
 17. The apparatus according to claim 16, whereinthe control unit is configured to reduce imaged motion of the portion ofthe subject's body associated with motion of the portion of thesubject's body by image tracking the set of image frames.
 18. Theapparatus according to claim 16, wherein the control unit is configuredto generate the set of image frames corresponding to image frames of theportion acquired during the given phase, by actuating the imaging deviceto acquire the plurality of image frames only when the cyclic activityis at the given phase.
 19. The apparatus according to claim 16, whereinthe imaging device is configured to acquire the plurality of imageframes throughout the cyclic activity, and wherein the control unit isconfigured to generate the set of image frames corresponding to imageframes of the portion acquired during the given phase by selecting imageframes corresponding to image frames of the portion acquired during thegiven phase from the plurality of image frames.
 20. The apparatusaccording to claim 16, wherein the control unit is configured togenerate an additional stabilized set of image frames of the portion ofthe subject's body, by identifying a further given phase of the cyclicactivity of the body system, and generating a set of the image framescorresponding to image frames of the portion acquired during the furthergiven phase.
 21. The apparatus according to claim 1, wherein the cyclicactivity includes a cardiac cycle of the subject, and wherein the sensorcomprises a sensor for sensing a phase of the subject's cardiac cycle.22. The apparatus according to claim 21, wherein the given phaseincludes an end-diastolic phase of the subject's cardiac cycle, andwherein the control unit is configured to generate a stabilized set ofthe image frames corresponding to image frames of the portion acquiredduring the end-diastolic phase of the subject's cardiac cycle.
 23. Theapparatus according to claim 21, wherein the sensor comprises an imageprocessor configured to sense movement of the portion of the subject'sbody by comparing image frames of the plurality of image frames to atleast one of the plurality of image frames.
 24. The apparatus accordingto claim 1, wherein the cyclic activity includes a respiratory cycle ofthe subject, and wherein the sensor comprises a sensor for sensing aphase of the subject's respiratory cycle.
 25. The apparatus according toclaim 24, wherein the sensor comprises an image processor configured tosense movement of the portion of the subject's body by comparing imageframes of the plurality of image frames to at least one of the pluralityof image frames.
 26. The apparatus according to claim 1, furthercomprising an instrument configured to be operated by a user, whereinthe control unit is configured to actuate the tool to perform thefunction, (a) in response to the sensor sensing that the cyclic activityis at the given phase thereof, and (b) in response to the instrumentbeing operated by the user.
 27. The apparatus according to claim 26,wherein the instrument is configured to provide force feedback to theuser that is independent of the cyclic activity.
 28. The apparatusaccording to claim 26, wherein the instrument is configured to provideforce feedback to the user that is smoothened with respect to the cyclicactivity.
 29. A method for use with a portion of a body of a subjectthat moves as a result of cyclic activity of a body system of thesubject, the method comprising: inserting a medical tool into theportion of the subject's body, the tool being configured to perform afunction; acquiring a plurality of image frames of the tool disposedwithin the portion of the subject's body; sensing a phase of the cyclicactivity; displaying a stabilized set of image frames of the tooldisposed within the portion of the subject's body; facilitated by thedisplaying of the stabilized set of image frames, actuating the tool toexecute an action selected from the group consisting of: performing thefunction and moving, in response to sensing that the cyclic activity isat a given phase thereof, and inhibiting the tool from executing theaction in response to sensing that the cyclic activity is not at thegiven phase thereof.
 30. The method according to claim 29, wherein thetool includes a valve configured to be implanted within the portion ofthe subject's body by being expanded within the portion, and whereinactuating the tool to perform the function comprises expanding thevalve.
 31. The method according to claim 29, wherein the tool includes aseptal-closure device configured to be implanted within the portion ofthe subject's body by being expanded within the portion, and whereinactuating the tool to perform the function comprises expanding theseptal-closure device.
 32. The method according to claim 29, whereinactuating the tool to perform the function comprises actuating a balloonto be inflated inside a lumen of the portion of the subject's body. 33.The method according to claim 29, wherein moving the tool comprisesmoving a tubular structure configured to bypass an occlusion of a bloodvessel within the portion of the subject's body.
 34. The methodaccording to claim 29, wherein the tool includes a myocardialrevascularization tool configured to sequentially apply arevascularization treatment to respective treatment sites within theportion of the subject's body, wherein actuating the tool to perform thefunction comprises actuating the tool to apply a revascularizationtreatment to a treatment site, and wherein moving the tool comprisesmoving at least a portion of the revascularization tool towardsuccessive treatment sites.
 35. The method according to claim 29,wherein the tool includes an ablation tool configured to sequentiallyablate respective ablation sites within the portion of the subject'sbody, wherein actuating the tool to perform the function comprisesactuating the tool to ablate an ablation site, and wherein moving thetool comprises moving at least a portion of the ablation tool towardsuccessive ablation sites.
 36. The method according to claim 29, whereinthe tool includes an injection tool configured to inject a substancewithin the portion of the subject's body, wherein actuating the tool toperform the function comprises actuating the tool to inject thesubstance, and wherein moving the tool comprises moving at least aportion of the tool toward an injection site.
 37. The method accordingto claim 29, wherein the tool includes a needle configured to suturetissue within the portion of the subject's body, wherein actuating thetool to perform the function comprises actuating the tool to suture thetissue, and wherein moving the tool comprises moving the needle towardsuccessive suturing sites.
 38. The method according to claim 29, whereinthe tool includes a needle configured to aspirate tissue from anaspiration site within the portion of the subject's body, whereinactuating the tool to perform the function comprises actuating theneedle to aspirate the tissue, and wherein moving the tool comprisesmoving the needle toward the aspiration site.
 39. The method accordingto claim 29, wherein actuating the tool to perform the functioncomprises actuating an occlusion-opening tool to perform anocclusion-opening action on an at least partial occlusion of a lumen ofthe portion of the subject's body.
 40. The method according to claim 39,wherein actuating the tool to perform the occlusion-opening actioncomprises moving the tool toward the occlusion, and wherein the methodfurther comprises retracting the tool from the occlusion after actuatingthe tool at the given phase of a first cycle and before the actuation ofthe tool at the given phase of a subsequent cycle.
 41. The methodaccording to claim 29, wherein displaying the stabilized set of imageframes comprises image tracking at least some of the plurality of imageframes to reduce imaged motion of the portion of the subject's bodyassociated with the cyclic activity.
 42. The method according to claim41, wherein displaying the stabilized set of image frames furthercomprises generating a set of tracked image frames corresponding toimage frames of the portion acquired during the given phase.
 43. Themethod according to claim 29, wherein displaying the stabilized set ofimage frames comprises displaying a set of the image framescorresponding to image frames of the portion acquired during the givenphase.
 44. The method according to claim 43, wherein displaying thestabilized set of image frames further comprises image tracking the setof image frames to reduce imaged motion of the portion of the subject'sbody associated with motion of the portion of the subject's body. 45.The method according to claim 43, wherein acquiring the plurality ofimage frames comprises acquiring the plurality of image frames only whenthe cyclic activity is at the given phase, and wherein displaying theset of image frames comprises displaying the plurality of acquired imageframes.
 46. The method according to claim 43, wherein acquiring theplurality of image frames comprises acquiring the plurality of imageframes throughout the cyclic activity, and wherein displaying the set ofimage frames comprises selecting image frames corresponding to imageframes of the portion acquired during the given phase from the pluralityof image frames.
 47. The method according to claim 43, furthercomprising displaying an additional set of stabilized images by sensinga further given phase of the cyclic activity of the body system, anddisplaying a set of the image frames corresponding to image frames ofthe portion acquired during the further given phase.
 48. The methodaccording to claim 29, wherein the cyclic activity includes a cardiaccycle of the subject, and wherein sensing the phase comprises sensing aphase of the subject's cardiac cycle.
 49. The method according to claim48, wherein the given phase includes an end-diastolic phase of thesubject's cardiac cycle, and wherein sensing the phase comprises sensingthe end-diastolic phase of the subject's cardiac cycle.
 50. The methodaccording to claim 48, wherein sensing the given phase comprisescomparing image frames of the plurality of image frames to at least oneof the plurality of image frames.
 51. The method according to claim 29,wherein the cyclic activity includes a respiratory cycle of the subject,and wherein sensing the phase comprises sensing a phase of the subject'srespiratory cycle.
 52. The method according to claim 51, wherein sensingthe given phase comprises comparing image frames of the plurality ofimage frames to at least one of the plurality of image frames.
 53. Themethod according to claim 29, wherein actuating the tool to execute theaction comprises actuating the tool to execute the action (a) inresponse to sensing that the cyclic activity is at the given phasethereof, and (b) in response to an instrument being operated by a user.54. The method according to claim 53, further comprising providing forcefeedback to the user that is independent of the cyclic activity.
 55. Themethod according to claim 53, further comprising providing forcefeedback to the user that is smoothened with respect to the cyclicactivity.
 56. Apparatus for use with a portion of a body of a subjectthat moves as a result of cyclic activity of a body system of thesubject, and for use with an imaging device for acquiring a plurality ofimage frames of the portion of the subject's body, a sensor for sensinga phase of the cyclic activity, a medical tool configured to perform afunction with respect to the portion of the subject's body, and adisplay configured to facilitate use of the tool by displaying imageframes of the portion of the subject's body, the apparatus comprising: acontrol unit configured to: generate a stabilized set of image frames ofthe portion of the subject's body, output the stabilized set of imageframes to the display, actuate the tool to perform the function inresponse to the sensor sensing that the cyclic activity is at a givenphase of the cyclic activity, and inhibit the tool from performing thefunction in response to the sensor sensing that the cyclic activity isnot at the given phase.
 57. Apparatus for use with a portion of a bodyof a subject that moves as a result of cyclic activity of a body systemof the subject, the apparatus comprising: an imaging device foracquiring a plurality of image frames of the portion of the subject'sbody; a sensor for sensing a phase of the cyclic activity; a medicaltool configured to mechanically perform an action during a single cycleof the cyclic activity with respect to the portion of the subject'sbody; and a control unit configured to: generate a stabilized set ofimage frames of the portion of the subject's body, and actuate the toolto mechanically perform the action in response to the sensor sensingthat the cyclic activity is at a given phase thereof.
 58. The apparatusaccording to claim 57, wherein the control unit is configured togenerate the stabilized set of image frames by generating a set of imageframes that are stabilized with respect to the given phase of the cyclicactivity.
 59. The apparatus according to claim 57, wherein the toolcomprises a balloon configured to apposition itself to a lumen of theportion of the subject's body during a single cycle by being inflated,in response to the sensor sensing that the cyclic activity is at thegiven phase thereof.
 60. The apparatus according to claim 57, whereinthe tool comprises a stent configured to be implanted by being expandedinside a lumen of the portion of the subject's body during a singlecycle of the cyclic activity, in response to the sensor sensing that thecyclic activity is at the given phase thereof.
 61. The apparatusaccording to claim 57, wherein the tool comprises a valve configured tobe implanted within the portion of the subject's body by mechanicallyexpanding within the portion during a single cycle of the cyclicactivity, in response to the sensor sensing that the cyclic activity isat the given phase thereof.
 62. The apparatus according to claim 57,wherein the tool comprises a septal-closure device configured to beimplanted within a heart of the subject by mechanically expanding withinthe heart during a single cycle of cardiac cyclic activity of thesubject, in response to the sensor sensing that the cyclic activity isat the given phase thereof.
 63. A method for use with a portion of abody of a subject that moves as a result of cyclic activity of a bodysystem of the subject, the method comprising: acquiring a plurality ofimage frames of the portion of the subject's body; sensing a phase ofthe cyclic activity; generating a stabilized set of image frames of theportion of the subject's body; and actuating a tool to mechanicallyperform an action during a single cycle of the cyclic activity, inresponse to sensing that the cyclic activity is at a given phasethereof.
 64. The method according to claim 63, wherein generating thestabilized set of image frames comprises generating a set of imageframes that are stabilized with respect to the given phase of the cyclicactivity.
 65. The method according to claim 63, wherein the toolincludes a balloon, and wherein actuating the balloon comprisesactuating the balloon to apposition itself to a lumen of the portion ofthe subject's body during a single cycle by being inflated in responseto sensing that the cyclic activity is at the given phase thereof. 66.The method according to claim 63, wherein the tool includes a stent, andwherein actuating the stent comprises implanting the stent by expandingthe stent inside a lumen of the portion of the subject's body during asingle cycle of the cyclic activity, in response to sensing that thecyclic activity is at the given phase thereof.
 67. The method accordingto claim 63, wherein the tool includes a valve, and wherein actuatingthe valve comprises implanting the valve by expanding the valve inside alumen of the portion of the subject's body during a single cycle of thecyclic activity, in response to sensing that the cyclic activity is atthe given phase thereof.
 68. The method according to claim 63, whereinthe tool includes a septal-closure device, and wherein actuating theseptal-closure device comprises implanting the septal-closure devicewithin a heart of the subject by expanding the septal-closure deviceinside the subject's heart during a single cycle of the cyclic activity,in response to sensing that the cyclic activity is at the given phasethereof.